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The femoro-sacral posterior angle: An anatomical sagittal pelvic parameter usable with dome-shaped sacrum
Abstract
The sagittal pelvic morphology modulates the individual alignment of the spine. Anatomical angular parameters were described as follows: the "Pelvic Incidence" (PI) and the Jackson's angle "Pelvic Lordosis" (PR-S1). Significant chains of relationships were expressed connecting these angles with pelvic and spinal positional parameters. This allows an individual assessment of the harmony of the sagittal spinal balance. But in case of spondylolysis with high-grade listhesis, the upper plate of the sacrum shows a dome-shaped deformity. The previous anatomical parameters are therefore imprecise. Indeed, the anterior part of the sacrum being inaccurate, an exact assessment of these angles becomes impossible. Therefore, we propose a new angular parameter named "Femoro-Sacral Posterior Angle" (FSPA): the angle between the posterior wall of the first sacral vertebra, always well definite, and the line connecting the posterior part of the sacral plate to the femoral axis. The validation of this parameter was performed and compared with the classical published parameters. It showed good inter-observer reliability, even with dome-shaped sacral plate. In spite of lower correlation with the positional parameters than those observed with PI or PR-S1, the FSPA appeared to be reliable and precise for an exact evaluation of the sagittal spino-pelvic balance is case of spondylo-listhesis with dome-shaped sacral endplate.
... Sagittal sacropelvic parameters, including sacral anatomic orienta-tion (SAO), pelvic incidence (PI), pelvic thickness (PTH), femoro-sacral posterior angle (FSPA), sacral table angle (STA), and sacral kyphosis (SK), were measured on each using IntelliSpace PACS ver. 4.4 Enterprise (Koninklijke Philips N.V., Amsterdam, Netherlands) [7,[15][16][17][18][19][20]. These sagittal sacropelvic measures have previously been subject to reliability analysis with excellent results [21]. ...
... FSPA was measured using a line from the bicoxofemoral axis to the posterosuperior corner of the sacrum and a line drawn along the posterior border of S1 (Fig. 3) [19]. STA was measured as the angle subtended by a line drawn along the sacral endplate and a line along S1 the posterior border ( Fig. 4) [21]. ...
... FSPA was developed for use in patients with a deformed sacral endplate where the identification of the anterior, center, or posterior margin is prone to significant interobserver error [19]. FSPA is perhaps easier to measure on a normal individual with the sacral measure utilizing the sacrum's posterior border rather than utilizing a line perpendicular to the sacral endplate. ...
Study design:
Retrospective analysis of computed tomography scans.
Purpose:
This study aims to determine the association of sagittal sacropelvic parameters with L5 spondylolysis.
Overview of literature:
The association of increased pelvic incidence (PI) and decreased sacral table angle (STA) with spondylolysis has been reported, but no study has simultaneously analyzed multiple sacropelvic variables to compare their association.
Methods:
In this study, computed tomography scans obtained to assess major trauma in patients aged >16 years were analyzed. Scans meeting one of the following criteria were excluded: abnormal anatomy, previous spine or hip/pelvis surgery, or spinal pathology, including deformity, infection, tumor, or trauma. sacral anatomic orientation (SAO), PI, pelvic thickness (PTH), femoro-sacral posterior angle (FSPA), STA, and sacral kyphosis (SK) were measured.
Results:
Overall, 202 scans were analyzed: 25 with L5 spondylolysis and 177 normal. Among the groups, a significant difference was observed in SAO (43.3° vs. 51.6°), PI (61.7° vs. 49.8°), STA (95.4° vs. 101.8°), and SK (31.0° vs. 23.7°). Based on the logistic regression analysis, only PI (odds ratio [OR], 1.074; 95% CI, 1.026-1.124) and STA (OR, 0.822; 95% CI, 0.734-0.920) remained significant predictors for the presence of spondylolysis. In the spondylolysis group, PI correlated significantly with PTH (r=-0.589), FSPA (r=0.880), and SK (r=0.576), whereas in the normal group, PI correlated significantly with FSPA (r=0.781) and SK (r=0.728).
Conclusions:
By simultaneously assessing multiple sacropelvic parameters, we associated increasing PI with L5 spondylolysis. Decreasing STA, which likely represents a chronic remodeling secondary to spondylolysis, was also associated with increased risk. Back pain in an adolescent or young adult with high PI or low STA should raise suspicion of a possible occult spondylolysis.
... Existing studies and reported values are summarized in Table 6. [1,4,7,8,11,15,19,25,[27][28][29][30][31][32][33][34][35][36][37][38][39][40] In this study, various radiographic parameters of sagittal spino-pelvic alignment were measured on sagittal spino-pelvic radiographs of 50 patients with chronic LBP and a comparison was done with the normative data reported for healthy Indian population. [26] Our hypothesis was that the variation in spino-pelvic parameters may predispose individuals to LBP. ...
... A number of studies associated PI with clinical indications, where PI was significantly higher for subjects with spondylolisthesis and other spino-pelvic pathologies. [11,15] Golbakhsh et al. [21] found no significant difference while comparing PI in LBP patients with and without lumbar instability at L5-S1, L4-L5, and L3-L4 levels. However, while evaluating PI separately for each level, they observed significantly lower values of PI in patients with lumbar instability of L5-S1 origin (P = 0.01). ...
... [27] A number of studies evaluated the relationship between PI and LLA, reporting significant correlation of r = 0.40 to 0.74 (P < 0.001). [1,10,14,15] In this study, we found a significant positive correlation in chronic low back patients (r = 0.594, P < 0.001). The strong correlation between PI and SHA, PT, and PRSI and PI and PT had also been reported. ...
Introduction: The sagittal spino-pelvic alignment patterns are still poorly understood in patients with chronic low back pain (LBP). Clinical observations suggest that aberrations of posture may play a role in the development of LBP. This study was undertaken with the aim to evaluate spino-pelvic parameters in patients with LBP and with a hypothesis that variation in these may predispose to LBP. Materials and Methods: Fifty patients (26 men and 24 women) with mean age 33.54 ± 8.33 years with a history of LBP of minimum 3 consecutive months constituted the study group and were subjected to standing sagittal spino-pelvic radiographs. Data were analyzed and compared with normative data. Results: The mean values of pelvic incidence (PI) and lumbar lordosis angle (LLA) were 48.52 ± 8.99 and 58.78 ± 9.51, respectively. The correlation of PI with lumbosacral angle (LSA), age, body mass index (BMI), and gender was not significant, but a significant correlation was observed with LLA, pelvic angle (PA), pelvic overhang (PO), pelvic tilt (PT), sacrofemoral distance (SFD), sacral horizontal angle (SHA), and sacropelvic translation (SPT). Sacral inclination angle (SIA), SHA, and PI were found to be significantly positively correlated with LLA, whereas pelvisacral angle (PSA), sacropelvic angle (PRS1), and SPT were found to be significantly negatively correlated. Statistically significant difference was observed only regarding pelvic thickness (PTH) and pelvic radius (PR) between patients with chronic LBP and healthy population. Conclusion: Most significant parameters (PI and LLA) used in spino-pelvic balance assessment have a positive significant correlation with majority of the other parameters and the harmony between them help in maintaining normal spinal column stability and alignment. Variation in some of the spino-pelvic parameters (PTH and PR) may predispose to LBP by putting stresses on the spinal column components and stabilizers.
... Several studies have evaluated the relationship between the position of the pelvis and spinal alignment [4][5][6][7][8][9][10][11][12][13][14][15][16]. However, it is important to know the values of these radiographic parameters in healthy individuals, without spinal disease. ...
... In the past three decades, increasing emphasis is being placed on quantitative evaluation of the parameters of sagittal spino-pelvic alignment as it is useful for clinical application and treatment of spino-pelvic pathologies. The harmony among spino-pelvic parameters is therefore of significant importance [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. However, for us to correctly understand the effects of the loss of sagittal balance on the quality of life of each individual, we must know the normal values of the parameters used to evaluate sagittal and spinopelvic balance in the population. ...
... A statistically significant difference was found between PI and gender in the present study with higher values of PI in [1]. However, a number of studies reported no relationship between PI and gender [7,8,14,15]. A positive correlation was found between PI and age in the study group (r = 0.36; p < 0.01) while Vialle et al. reported no relationship in normal adults [1]. ...
Introduction:
There is increasing emphasis on the sagittal spino-pelvic alignment and its interpretation is of critical importance in the management of spinal disorders. A cross-sectional study of several spino-pelvic radiographic parameters was conducted to determine the physiological values of these parameters, to calculate the variations of these parameters according to epidemiological data, and to study the relationships among these parameters.
Material and method:
Fifty normal healthy volunteers (29 males and 21 females) with no history of back pain were selected and were subjected to standing sagittal spino-pelvic radiographs. All the measurements of various radiographic parameters were performed with use of a software program. A statistical analysis was done to study the relationships among them.
Results:
The mean values of pelvic incidence (PI) and lumbar Lordosis Angle (LLA) were 48.52 ± 8.99 and 58.78 ± 9.51, respectively. There was statistical difference between male and female parameters in LLA, lumbo-sacral angle (LSA), sacral horizontal angle (SHA), sacral inclination angle (SIA), sacropelvic angle (PRS1), pelvisacral angle (PSA), and PI. A majority of parameters had higher values for female subjects when compared to male subjects. PI was positively correlated with LLA, pelvic angle (PA), pelvic overhang (PO), pelvic tilt (PT), sacrofemoral distance (SFD), SHA, and sacropelvic translation (SPT), which were highly significant, whereas LLA was positively correlated with SHA and SIA only. PI and LLA were both negatively correlated with PSA, pelvic thickness (PTH), and PRS1.
Conclusions:
This study presents the various spino-pelvic radiographic parameter values of a sample of the normal asymptomatic Indian population. There was significant difference in radiographic parameters between males and females in about half of the parameters studied in the sample. The values obtained are comparable with the values presented as normal in the literature. A comparison of the study results with data published about other populations revealed no differences in any of the pelvic parameters between the Indian, Brazilian, and Korean populations.
... Notably, we believe that the difference in the anatomical structure or living habits of Asians and Caucasians resulted in the differences in mean PI. Although there have been no studies designed to analyze the association between race and PI, the observation that mean PIs measured from Asians are generally lower than mean PIs measured from Caucasians requires further investigation (Table 3) 1,5,7,13,14,[18][19][20][21]23,31,36,37) . Moreover, a direct comparison could not be made with our study results due to the lack of reports on PT or SS measured from CT. ...
... Numerous studies have reported the mean PIs measured by X-ray over the preceding 30 years. Among them, 8 studies measured pelvic parameters in more than 100 normal subjects in addition to abnormally balanced people (Table 4) 5,7,20,23,27,31,36,37) . The lowest mean PI in these subjects was 50.2°±10.6°, ...
... The lowest mean PI in these subjects was 50.2°±10.6°, which was reported by Legaye et al. 23) , and the highest mean PI was 54.7°± 10.6°, which was reported by Vialle et al. 37) . Although the measurements from these previous studies were not too different from 50.2°±9.0°, ...
Objective:
Computed tomography (CT), rather than conventional 2-dimensional radiography, was used to scan and measure pelvic parameters. The results were compared with measurements using X-ray.
Methods:
Pelvic parameters were measured using both CT and X-ray in 254 patients who underwent both abdomino-pelvic CT and X-ray at the pelvic site. We assessed the similarity of the pelvic parameters between the 2 exams, as well as the correlations of pelvic parameters with sex and age.
Results:
The mean values of the subjects' pelvic parameters measured on X-ray were: sacral slope (SS), 31.6°; pelvic tilt (PT), 18.6°; and pelvic incidence (PI), 50.2°. The mean values measured on CT were: SS, 35.1°; PT, 11.9°; and PI, 47.0°. PT was found to be 4.07° higher on X-ray and 2.98° higher on CT in women, with these differences being statistically significant (p<0.001, p<0.001). PI was 4.10° higher on X-ray and 2.78° higher on CT in women, with these differences also being statistically significant (p<0.001, p=0.009). We also observed a correlation between age and PI. For men, this correlation coefficient was 0.199 measured using X-ray and 0.184 measured using CT. For women, this correlation coefficient was 0.423 measured using X-ray and 0.372 measured using CT.
Conclusion:
When measured using CT compared to X-ray, SS increased by 3.5°, PT decreased by 6.7°, and PI decreased by 3.2°. There were also statistically significant differences in PT and PI between male and female subjects, while PI was found to increase with age.
... There are 2 methods for measuring pelvic tilt, one using lateral radiographs [13,14,15] and the other using threedimensional (3D) measurement by computed tomography (CT) scan [12,16,17]. While 3D measurement allows alignment parameters to be determined with 1 degree and 1 mm accuracy [18], the required CT scan involves a high cost and also requires the software for analysis. ...
... While 3D measurement allows alignment parameters to be determined with 1 degree and 1 mm accuracy [18], the required CT scan involves a high cost and also requires the software for analysis. Several reports in the literature have demonstrated that pelvis tilt from lateral radiographs is easily measured, convenient, and inexpensive [14,15,19]. ...
... Consequently, it may be difficult for observers to identify the line parallel to superior endplate of sacrum. Legaye [15] reported on measurement of SS by 7 different observers from lateral radiographs. He demonstrated that the standard deviation of SS when the superior plate of sacrum was dome-shaped was approximately 4 times larger than when the radiograph appeared normal. ...
Background: Malpositioning during total hip arthroplasty may cause dislocation, pain, and other complications. To evaluate the potential of sacral slope (SS) as a reliable parameter of pelvic flexion. Methods: We developed a model of pelvic flexion to determine the intraobserver and interobserver variability and reliability of SS measurements by lateral radiography by three independent observers. Results: Measurement error was 1.2° and the intraobserver reliability was moderate to substantial (Interclass correlation coefficient: 0.31 to 0.66). Based on the Spearman-Brown formula, the measurement is reliable if it is done at least seven times by two observers, and four times by three observers. Conclusions: The data suggest that measurement of SS of pelvic flexion is a clinically useful parameter for the optimization of THA conditions.
... To simulate lateral bending movements, the initial sensor orientation was gradually increased through 0 • to 50 • pitch (rotation about Y in Figure 2) in 10 • increments, from 0 • to 20 • of twist (rotation about X) in 5 • increments, and via a combination of pitch and twist. Larger pitch angles were explored due to the reported sacral pitch angles commonly reaching 50 • [27]. jig) with an attached retroreflective marker was used to time-synchronize the accele eter data with the OEM data. ...
... To simulate lateral bending movements initial sensor orientation was gradually increased through 0° to 50° pitch (rotation a Y in Figure 2) in 10° increments, from 0° to 20° of twist (rotation about X) in 5° increm and via a combination of pitch and twist. Larger pitch angles were explored due t reported sacral pitch angles commonly reaching 50° [27]. Once the initial orientation was established, the jig was moved through 40°, 80° 120° of simulated forward bending, or 40° and 80° of simulated lateral bending, with movement repeated three times for each bending angle and each sensor orientation. ...
Accelerometers have been widely used for motion analysis. The effect of initial sensor orientation (ISO) on the derived range of motion (ROM) is currently unexplored, limiting clarity in understanding error. This two-step study systematically explored the effect of ISO on the error of accelerometer-derived range of motion (ROM) and the effect of a proposed correction algorithm. Accelerometer data were used to compute peak and through-range ROM across a range of ISO and movement angular velocities up to 148° s−1 compared to an optoelectronic gold-standard. Step 1 demonstrated that error increased linearly with increasing ISO offsets and angular velocity. Average peak ROM RMSE at an ISO of 20° tilt and twist was 5.9° for sagittal motion, and for an ISO of 50° pitch and 20° twist, it was 7.5° for frontal plane ROM. Through-range RMSE demonstrated errors of 7–8° for similar ISOs. Predictive modeling estimated a 3.2° and 3.7° increase in peak and through-range sagittal plane error for every 10° increase in tilt and twist ISO. Step 2 demonstrated error reduction utilizing mathematical correction for ISO, resulting in <1° mean peak error and <1.2° mean through-range ROM error regardless of ISO. Accelerometers can be used to measure cardinal plane joint angles, but initial orientation is a source of error unless corrected.
... with high PI (>60°) who are undergoing MLF with versus without SIJF. 6,[11][12][13][14] Diagnoses for the model population included spondylolisthesis; lumbosacral intervertebral disc disorder; adult degenerative scoliosis; post-laminectomy syndrome; and flat back syndrome. The model population excludes patients with morbid obesity (BMI 40+), heavy smoking, uncontrolled diabetes (A1C > 7.5%), low T-score (severe osteoporosis), congenital neuromuscular disease, prior pelvic or SIJ fixation, and grade IV spondylolisthesis. ...
... 11 Assuming a mean PI of 50° (standard deviation of 10°) in normal populations, 15.9% of patients have high PI (>60°). 6,[12][13][14] Assuming statistical independence, 6.5% of patients undergoing lumbar fusion are both obese and have high PI, whereas 57% of patients are either obese or have high PI. Hence, the applicable high-risk population likely ranges from 6.5% to 57% of MLF patients, which merits further research to more precisely define the true population at high risk. ...
Purpose
Multi-level lumbar fusion to the sacrum (MLF) can lead to increased stress and angular motion across the sacroiliac joint (SIJ), with an incidence of post-operative SIJ pain estimated at 26–32%. SIJ fusion (SIJF) can help obviate the need for revisions by reducing range of motion and screw stresses. We aimed to evaluate the cost-utility of MLF + SIJF compared to MLF alone among high-risk patients from a payer perspective, where high risk is defined as high body mass index and high pelvic incidence.
Methods
A Markov process decision-analysis model was developed to evaluate cumulative 5-year costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER) of MLF + SIJF compared to MLF alone using published data; costs from Medicare claims data analyses and health state utility values (derived from EQ-5D) informed by three prospective, multicenter, clinical trials. The base case assumed a reduction in post-operative SIJ pain from 30% to 10% (relative risk reduction [RRR] of 67%). Costs and utilities were discounted 3% annually. The ICER is reported in 2020 US dollars. One-way, multi-way, and probabilistic sensitivity analyses were performed.
Results
With an assumed 30% incidence of SIJ pain after MLF alone, stabilizing with SIJF was associated with an additional 5-year cost of $2421 and a gain of 0.14 QALYs, resulting in an ICER of $17,293 per QALY gained (similar to total knee arthroplasty and more favorable than open discectomy). ICERs were most sensitive to the RRR of post-operative SIJ pain conferred by SIJF, time horizon, and probability of successful treatment with MLF alone. At a willingness-to-pay threshold of $50,000/QALY gained, MLF + SIJF has a 97.7% probability of being cost-effective in the target patient population.
Conclusion
Fusing the SIJ in high-risk patients undergoing MLF was cost-effective when the incidence of post-operative SIJ pain after MLF alone exceeds approximately 25%, providing value-based healthcare from a payer perspective.
... It has been argued that low angulation of the lumbar vertebra may be associated with increased tendency to intervertebral disc herniation, and pain in the lower back, but with scarcity of reliable quantitative reference data, therapists and spinal heath Physicians rely more on measurements based on assumptions 2,6,7,10,11 .Other investigators, 12and13 posit that even in asymptomatic populations,detailed understanding of vertebral spine morphology is necessary to facilitate rapid evaluation, and diagnostic conclusion. Objectives were then designed to provide reference values, analyze any association between angle of lordosis and selected demographic factors such as age and gender, find out how angle of lardosis of Nigerians Inclusion criteria: Film reports Of Nigerians aged 18-77 years screened and certified free of bony abnormalities were used to ensure that besides the symptom complex that forced the ordering of X-rays, they had no skeletal abnormalities. ...
... Other authors 21,28,23 have reported similar findings of sex related differences. 0ur findings however contradict those by 5,10,12,25,27,29,30 who found no significant differences between male and female subjects with respect to angle of lumbar lordosis. Fernand and Fox 13 , proposed that Lumbar lordotic angle in excess of 68 degrees constitutes hyperlordosis and angle values below 23 degrees, hypolordosis. ...
Objectives: For Nigerian Africans, quantitative reference values of osteometric parameters of the human spine are scarce. This study was therefore carried out to metrically evaluate and document the characteristics of the Lumbar lordotic angle, in a population of Nigerians. Materials & Method: Using the Cobb 4-line method, we studied 300 lateral radiographs selected from three tertiary health facilities. There were 156 females (52%) and 144 males (48%) with age range between 18 and 76years. Results were analyzed statistically with the computer based SPSS Version 17, Chicago IL. Taking a confidence level of 0.05 as indicative of statistical significance, the student's t-test was used to estimate differences between means, and a probability density function curve ,to evaluate the distribution pattern of the angle of lumbar lordosis. Results: Mean (± SD) of the Lumbar lordotic angle was 48.45 0 ± (9.28 0). A statistically significant association was found between Lumbar lordotic angle and age (P<0.05). Females had significantly higher Lumbar lordotic angles compared with males (P<0.05). Variations were also observed between the lumbar lordotic angles of Nigerians and those of Caucasians. These results will be useful in many areas of medical practice, and research.
... The convenience sampling method was employed and the participants recruited through phone conversations, direct communication during health talks and conferences as well as by use of posters and radio. The minimum sample size was determined using formula provided by Portney and Watkins [29] , Lehana [30] and European Commission. [31] and a total of 142 subjects were used for the study ...
... Other investigators [12,19,22,23,28,29,30] argued that range 25-57° should be used as normal reference values for Caucasians. However Kim [18], in a more recent study recommended 30-40° to be used as reference values. ...
The study determined the Lumbosacral angle (LSA) of male subjects and evaluated its relationship to age, BMI and Waist-Hip ratio. Lateral radiographs of one hundred and forty-two informed healthy male volunteers between the age of 18-60 were studied using Ferguson's method, and analyzed with respect to age, waist hip ratio (WHR) and body mass index (BMI).. The result showed the average value for Lumbosacral angle was 34.06 0 ± 0.56 0 , the body weight was 70.34 ± 1.02Kg, and BMI was 24. 64 ± 0.38Kgm-2. Angle values were observed to increase with age up to 32years, followed by a sinusoidal increase and decrease pattern thereafter. Significant correlations were observed between LSA and Body weight as well as between LSA and BMI (p<0.05). The Lumbosacral angle of males in Port-Harcourt, South South Nigeria is within the range of literature derived measurement values worldwide , but lower than the average reported from previous studies on other Nigerian populations.
... Pelvic incidence (PI), first introduced by Legaye et al. [1,2], is defined as the angle between the line perpendicular to the sacral endplate at its midpoint and a line connecting this point to the axis of the femoral head. Of all pelvic parameters, PI seems to be the most important one which dictates ideal sacral orientation and therefore, ideal lumbar lordosis. ...
... The challenge of fixed PI was first proposed by Legaye et al. [2], which also postulated a theory that unstable SI joint would change PI. Followed Legaye's study, Bao et al. [6] demonstrated that pelvic retroversion generates a reaction force on the SI joint in patients with sagittal malalignment and thus destabilizes the SI joint, particularly in the presence of combined SI joint degeneration. ...
Study design:
A retrospective cross-sectional study.
Objective:
This study aims to determine whether the sacroiliac (SI) joint motion correlated to pelvic incidence (PI) change from standing to supine position in patients with degenerative spinal diseases.
Summary of background data:
PI was found an unstable parameter after adolescence as the fixed nature of PI was challenged by several studies. The SI joint has been shown to have some motion, age-related degenerative changes of cartilage and SI ligaments contribute to SI joint instability.
Methods:
The study contains both specimen study and radiographic study. One human specimen was acquired, on which PI was measured with different sacrum-ilium positions. In radiographic study, patients with old thoracolumbar fracture, lumbar disc herniation, stenosis, and spondylolisthesis were included. Ankylosing spondylitis (AS) patients were also included as control group. PI was measured on standing x-rays and scanogram of computed tomography images in supine position.
Results:
Specimen study result revealed that SI motion would lead to the change of PI with fixed pelvic thickness. In radiographic study, 101 patients with different etiology and 30 AS patients were included. After stratifying into different age groups, standing PI was significantly larger than supine PI in each age groups (P = 0.002, <0.001, and <0.001, respectively). In patients with degenerative diseases, PI was significantly larger on standing position than that on supine position. ΔPI showed no significant difference across etiologies. However, in AS patients, standing PI and supine PI revealed no significant difference (P = 0.528).
Conclusion:
Mobile SI joint may be the cause of increased PI in the aging spine. The dynamic change of PI is etiology-independent if the SI joint was not fused. Older patients have greater position-related change of PI.Level of Evidence: 4.
... Anatomic measures taken are shown in Table 1. The components of the PI, pelvisacral angle (PSA), pelvic thickness (PTH; Fig. 1), sacral anatomic orientation (SAO; Fig. 2), sacropelvic angle (PRS1), femorosacral pelvic angle (FSPA), and sacral table angle (STA; Fig. 3) are well described (During et al., 1985;Duval-Beaupere et al., 1992;Jackson et al., 2000;Inoue et al., 2002;Legaye, 2007;Peleg et al., 2007;Vrtovec et al., 2012a). For sacral kyphosis (SK), we used a line through the midpoint of the sacral endplate to the midpoint of the S1-2 junction subtended by a line from the S1-2 junction midpoint to the midpoint of S4 caudally (Fig. 4). ...
... The FSPA was initially reported having given consideration to the difficulty in measuring PI in patients with a domed or deformed sacral endplate (Legaye, 2007). It is intuitive that the FSPA therefore be closely correlated to PI. ...
Normal values for spinal alignment are often based on the pelvic incidence (PI), defined as the angle subtended by a line from the bicoxofemoral axis to the midpoint of the sacral endplate and a line perpendicular to the midpoint. Despite widespread use, determinants of its values remain obscure. The aim of this study was to determine correlation of sacropelvic parameters with the PI on computed tomography (CT). CT scans performed for trauma were identified over a 1‐year period. Patients aged over 16 were included. PI, sacral anatomic orientation, sacral table angle (STA), sacral kyphosis (SK), pelvic thickness (PTH), femorosacral pelvic angle, pelvisacral angle, and sacropelvic angle were measured. Additional novel measures including crest‐to‐pubis distance, crest‐to‐sacrum distance (CSD), inlet distance, outlet distance, and inlet–outlet angle were taken. One hundred and seventy‐seven scans were analyzed. Mean age 44.3 years; 62% male. The mean PI was 50.1 (SD 10.8; range 29–87). SK (r = 0.769), inlet–outlet angle (r = −0.533), PTH (r = −0.370), CSD (r = 0.290), and STA (r = −0.276) significantly correlated with PI. Multivariate analysis developed a predictive equation of: PI = 101.45 − (0.52 × STA) + (0.67 × SK) − (0.34 × inlet–outlet angle), with an adjusted R² 0.734 (P < 0.001). Measures that represent the sacral morphology, particularly SK, and the position of the sacrum in space correlated strongly with the PI and contributed strongly to a predictive equation. These findings may direct further efforts to explore how the PI is determined and therefore how it may be modified. Clin. Anat. 33:237–244, 2020. © 2019 Wiley Periodicals, Inc.
... Third, we did not image the entire spine; however, we found strong correlations using lumbar images alone. Fourth, the accuracy of measuring sacral slope angles is dependent on the radiographic definition of the anterior part of the sacrum [27]. We did not evaluate the accuracy of methods for measuring pelvic, lumbar, and femoral angles. ...
... We did not evaluate the accuracy of methods for measuring pelvic, lumbar, and femoral angles. The accuracy of the measurements is disputed in the literature, since accuracy is dependent on the ability to identify landmarks in the presence of degenerative diseases of the spine [18,27]. However, excellent intra-and interobserver reliability for measuring sacral slope and lumbar lordosis angles on lateral radiographs has been reported [9]. ...
Background
Sitting pelvic tilt dictates the proximity of the rim of the acetabulum to the proximal femur and, therefore, the risk of impingement in patients undergoing total hip arthroplasty (THA). Sitting position is achieved through a combination of lumbar spine segmental motions and/or femoroacetabular articular motion in the lumbar-pelvic-femoral complex. Multilevel degenerative disc disease (DDD) may limit spine flexion and therefore increase femoroacetabular flexion in patients having THAs, but this has not been well characterized. Therefore, we measured standing and sitting lumbar-pelvic-femoral alignment in patients with radiographic signs of DDD and in patients with no radiographic signs of spine arthrosis. Questions/purposesWe asked: (1) Is there a difference in standing and sitting lumbar-pelvic-femoral alignment before surgery among patients undergoing THA who have no radiographic signs of spine arthrosis compared with those with preexisting lumbar DDD? (2) Do patients with lumbar DDD experience less spine flexion moving from a standing to a sitting position and therefore compensate with more femoroacetabular flexion compared with patients who have no radiographic signs of arthrosis? Methods
Three hundred twenty-five patients undergoing primary THA had preoperative low-dose EOS spine-to-ankle lateral radiographs in standing and sitting positions. Eighty-three patients were excluded from this study for scoliosis (39 patients), spondylolysis (15 patients), not having five lumbar vertebrae (7 patients), surgical or disease fusion (11 patients), or poor image quality attributable to high BMI (11 patients). In the remaining 242 of 325 patients (75%), two observers categorized the lumbar spine as either without radiographic arthrosis or having DDD based on defined radiographic criteria. Sacral slope, lumbar lordosis, and proximal femur angles were measured, and these angles were used to calculate lumbar spine flexion and femoroacetabular flexion in standing and sitting positions. Patients were aligned in a standardized sitting position so that their femurs were parallel to the floor to achieve approximately 90° of apparent hip flexion. ResultsAfter controlling for age, sex, and BMI, we found patients with DDD spines had a mean of 5° more posterior pelvic tilt (95% CI, −2° to −8° lower sacral slope angles; p < 0.01) and 7° less lumbar lordosis (95% CI, −10° to −3°; p < 0.01) in the standing position compared with patients without radiographic arthrosis. However, in the sitting position, patients with DDD spines had 4° less posterior pelvic tilt (95% CI, 1°–7° higher sacral slope angles; p = 0.02). From standing to sitting position, patients with DDD spines experienced 10° less spine flexion (95% CI, −14° to −7°; p < 0.01) and 10° more femoroacetabular flexion (95% CI, 6° to 14°; p < 0.01). Conclusions
Most patients undergoing THA sit in a similar range of pelvic tilt, with a small mean difference in pelvic tilt between patients with DDD spines and those without radiographic arthrosis. However, in general, the mechanism by which patients with DDD of the lumbar spine achieve sitting differs from those without spine arthrosis with less spine flexion and more femoroacetabular flexion. Clinical RelevanceWhen planning THA, it may be important to consider which patients sit with less posterior pelvic tilt and those who rotate their pelvises forward to achieve a sitting position, as both mechanisms will limit or reduce the functional anteversion of the acetabular component in a patient with a THA. Our study provides some additional perspective on normal relationships between pelvic tilt and femoroacetabular flexion, but further research might better characterize this relationship in outliers and the possible implications for posterior instability after THA.
... It has been argued that low angulation of the lumbar vertebra may be associated with increased tendency to intervertebral disc herniation, and pain in the lower back, but with scarcity of reliable quantitative reference data, therapists and spinal heath Physicians rely more on measurements based on assumptions 2,6,7,10,11 .Other investigators, 12and13 posit that even in asymptomatic populations,detailed understanding of vertebral spine morphology is necessary to facilitate rapid evaluation, and diagnostic conclusion. Objectives were then designed to provide reference values, analyze any association between angle of lordosis and selected demographic factors such as age and gender, find out how angle of lardosis of Nigerians Inclusion criteria: Film reports Of Nigerians aged 18-77 years screened and certified free of bony abnormalities were used to ensure that besides the symptom complex that forced the ordering of X-rays, they had no skeletal abnormalities. ...
... Other authors 21,28,23 have reported similar findings of sex related differences. 0ur findings however contradict those by 5,10,12,25,27,29,30 who found no significant differences between male and female subjects with respect to angle of lumbar lordosis. Fernand and Fox 13 , proposed that Lumbar lordotic angle in excess of 68 degrees constitutes hyperlordosis and angle values below 23 degrees, hypolordosis. ...
Objectives: For Nigerian Africans, quantitative reference values of osteometric parameters of the human spine are scarce. This study was therefore carried out to metrically evaluate and document the characteristics of the Lumbar lordotic angle, in a population of Nigerians.
Materials & Method: Using the Cobb 4-line method, we studied 300 lateral radiographs selected from three tertiary health facilities. There were 156 females (52%) and 144 males (48%) with age range between 18 and 76years. Results were analyzed statistically with the computer based SPSS Version 17, Chicago IL. Taking a confidence level of 0.05 as indicative of statistical significance, the student’s t –test was used to estimate differences between means, and a probability density function curve ,to evaluate the distribution pattern of the angle of lumbar lordosis.
Results: Mean (± SD) of the Lumbar lordotic angle was 48.450 ± (9.280). A statistically significant association was found between Lumbar lordotic angle and age (P
... Furthermore, the results of comparatively lower reliability of measuring FS-PI than P-PI statistically and high correlation between P-PI and CT-PI mean that large angle of radiograph's projection causes diffi culty in identifying anatomical landmarks, particularly sacral endplate ( Figure 4A, B ), because the projection of the full-spine lateral standing radiograph is centered on the 12th thoracic vertebra and that of the pelvis lateral standing radiograph is centered on the S1 endplate. Legaye,20 in the comparative study of reliability of measuring spinopelvic parameters in the patients with and without dome-shaped sacrum, showed the larger scattering of values of PI in patients with dome-shaped sacrum than in the patients with normal sacral plate by standard deviation (5.3 ° and 1.3 ° , respectively) and proposed that in degenerative pathologies, especially with dome-shaped sacrum, the inaccurate visualization of the superior plate of S1 does not allow an exact measurement of PI. However, in the present study, we did not verify the infl uence of rounding endplate of sacrum proposed by Legaye 20 ...
... Legaye,20 in the comparative study of reliability of measuring spinopelvic parameters in the patients with and without dome-shaped sacrum, showed the larger scattering of values of PI in patients with dome-shaped sacrum than in the patients with normal sacral plate by standard deviation (5.3 ° and 1.3 ° , respectively) and proposed that in degenerative pathologies, especially with dome-shaped sacrum, the inaccurate visualization of the superior plate of S1 does not allow an exact measurement of PI. However, in the present study, we did not verify the infl uence of rounding endplate of sacrum proposed by Legaye 20 ...
Prospective comparative study of measuring pelvic incidence (PI) among standing X-ray images of whole spine and pelvis, and computed tomography (CT) in a cohort of patients.
To analyze accuracies in measuring PI and other spino-pelvic parameters.
Previous reports indicated relatively low agreement in measuring PI even among experienced spinal surgeons; intra- and inter-rater reliability in manual measuring PI were 0.69 (0.62-0.74) and 0.41 (0.36-0.45), respectively, the mean interclass correlation coefficient (ICC) value of manual measuring PI was 0.881. No study compared PI on standing X-rays to that measured in CT images.
Consecutive 120 spinal disease patients (38 patients had history of hip arthroplasty) who admitted to our hospital from April, 2012 for 6 months were enrolled. Subjects had full-spine lateral standing X-ray, standing X-ray of pelvis, and CT. PI on full-spine lateral standing X-ray (FS-PI) and that on pelvis lateral standing X-ray (P-PI) were measured manually by two experienced spinal surgeons. Intra- and inter-observer reliability of the measurements were analyzed by using ICC. On CT images, PI was measured using three-dimensional CT image software (CT-PI). PI among three different imaging modalities were evaluated using correlation coefficients.
In whole spine X-ray images, the intra- and inter-observer agreement rates with measurements in PI (0.84 and 0.79, respectively) and sacral slope (SS) (0.87 and 0.83, respectively) were lower than in pelvic tilt (PT) (0.98 and 0.96, respectively) and PI - lumbar lordosis (LL) (0.97 and 0.97, respectively). The correlation coefficient between P-PI and CT-PI was higher (0.95) than between FS-PI and CT-PI (0.81), and between FS-PI and P-PI (0.85).
The reliability of measuring PI is comparatively lower than that of other spino-pelvic parameters, and the variability of PI measurement is mainly due to difficulty of precise identifying sacral endplate.
... Pelvic morphology and spinopelvic balance abnormalities are among the most important factors causing the development of spondylolisthesis. Legaye et al. 19 reported the PI as 50.2±10.6 in the normal elderly population, while this angle was 62±11 in patients with listhesis. Also, Liu 20 and Funao 21 likewise showed that PI was higher than the normal population in their study. ...
Background: Spondylolisthesis is a deformity in which the upper segment is displaced anteriorly or posteriorly in the spine relative to the lower segment. In this pathology, which often causes instability, surgical treatment may be required. Also, patient’s radiological images should be evaluated carefully before treatment. We aimed to analyze clinical and radiological data with spinopelvic angles of the lumbar spondylolisthesis patients in our research. Material Method: 6593 patients who applied to the neurosurgery outpatient clinic with complaints of low back pain between January 2020 - December 2023 were retrospectively analyzed. The radiological findings of patients with spondylolisthesis, whose lumbar MRI and lumbar CT were obtained appropriately along with X-ray were evaluated in detail. Age, gender, listhesis level and degree, Cobb angle, pelvic incidence, pelvic tilt, sacral slope angle, Modic degeneration, vacuum phenomenon, annulus rupture, schmorl nodule, facet hypertrophy, osteophyte, maximum AP central canal diameter and joint lysis has been examined in these patient tests. The relationships of these data with each other were evaluated statistically. Results: 58 female and 5 male patients were found to be eligible for the study. Mean age was 59 (min 22, max 81). Grade 1 listhesis was detected in 52 of the patients. Listhesis was observed at the level of L5-S1 in 31 patients, L4-L5 in 24 patients and L3-L4 in 8 patients. A direct correlation was found between age with vacuum phenomenon, osteophyte, presence of L5-S1 listesis and lysis. Similar correlation was between pelvic incidence with sacral slop angle, facet hypertrophy and modic type 2 degeneration. Also, there was a direct correlation between pelvic incidence with pelvic tilt; between facet hypertrophy with vacuum phenomenon and lysis; ligamentum hypertrophy with vacuum phenomenon; and facet hypertrophy with lower level listesis (p 0.05). Discussion and Conclusion: Spondylolisthesis is an important problem that requires treatment in spine surgery. Radiologically determined parameters can give important findings about the severity of this pathology. These findings should be taken into consideration in the treatment of spondylolisthesis.
... These findings, including the KF cutoff and the observed relationship between the KF and global spinopelvic sagittal alignment, have potential for use in the screening of patients undergoing knee-plane radiographs to identify spinopelvic sagittal-imbalance conditions. Moreover, we believe that these findings will serve as a more convenient index for evaluating global balance and assessing treatment outcomes in patients with spinal deformities, particularly in cases in which there may be challenges in recognizing radiographic parameters in the sacral pelvic region [17,18]. However, the compensatory mechanisms of the whole body consist of many alignments in mobility [3,5], and it is uncertain whether a single variable, such as KF, can accurately reflect an individual patient's state of balance maintenance. ...
Background:
The aim of this study was to investigate the differences in the involvement of whole-body compensatory alignment in different conditions of spinopelvic sagittal balance (compensated/decompensated).
Methods:
We enrolled 330 individuals who underwent medical checkups and divided them according to sagittal vertical axis (SVA): for the compensated group, this was <4 cm, (group C) and for the decompensated group, it was ≥4 cm, (group D). The correlation between the lack of ideal lumbar lordosis (iLL), which was calculated by using the Schwab formula, and the compensatory radiographic parameters in each group was analyzed. The threshold value of knee flexion (KF) angle, which indicated spinopelvic sagittal imbalance (SVA ≥ 4), was determined by a ROC-curve analysis.
Results:
The correlation analysis of the lack of iLL and each compensatory parameter showed a strong correlation for pelvic tilt (PT) (r = -0.723), and a weak correlation for thoracic kyphosis (TK) (r = 275) in Group C. In Group D, the correlations were strong for PT (r = -0.796), and moderate for TK (r = 0.462) and KF (r = -0.415). The optimal cutoff value for the KF angle was determined to be 8.4 degrees (sensitivity 89%, specificity 46%).
Conclusions:
The present study shows differences between compensated/decompensated spinopelvic sagittal balance in the correlation strength between lack of iLL and whole-body compensatory parameters.
... El rango de valor para la pendiente sacra fue de 32 o a 49 o y de 3 o a 18 o para la inclinación pélvica. 20 Existe una relación entre estos últimos tres parámetros. La incidencia pélvica es igual a la suma aritmética de la pendiente sacra y la inclinación pélvica (PI = PT + SS) 21-23 (Figura 1). ...
... In several X-rays from the total 77 subjects, the projection of the XR beam from a more inferior position causes the sacral endplate to become circular in shape and more difficult to precisely delineate (Fig. 6a), leading to a discrepancy in PI measurement on XR compared to standard CT and 3D CT (Fig. 6b, c). In a study by Legaye comparing reliability of measuring spinopelvic parameters, including PI, in patients with and without dome-shaped sacrum, there was a larger spread of values of PI in patients with dome-shaped sacra compared to patients with a flat sacral plate (standard deviation of 5.4 and 1.3, respectively), likely due to ambiguity in evaluating the tilt of the sacral endplate with dome-shaped sacra [24]. In another study by Chen et al., the group reported that depending on whether the sacral endplate was concave or convex side anteriorly, PI measured on XR would be smaller or larger compared to CT, respectively, due to the projectional nature of the XR [19]. ...
PurposePelvic incidence (PI) is a position independent parameter used to quantify spinopelvic sagittal balance. PI is generally measured on lateral radiographs, but more recent studies have suggested better accuracy with standard CT scans versus three-dimensional (3D) CT scans. This study compares PI obtained from lateral XR, standard CT scan and CT scan with 3D reconstruction.
MethodsA total of 77 subjects with lateral XRs of the pelvis or lumbosacral spine and CT scans of the pelvis were randomly selected. Pelvic incidence on lateral XRs, standard CT scans and CT scans utilizing multiplanar reconstruction were measured and compared using intraclass correlation coefficients (ICC). PI was also measured on serial images in 28 individuals using the same imaging modality within 3 years and evaluated using ICC.ResultsMean ± SD of PI measurements on XR, standard CT and CT with 3D reconstruction were 56° ± 13°, 53° ± 12° and 53° ± 12°, respectively, demonstrating a small but significant elevation of PI measurement on XR (P < 0.001). ICC values demonstrated a higher correlation between standard CT and 3D CT (ICC 0.986), compared to XR and standard CT (ICC 0.934) and XR and 3D CT (ICC 0.937). PI measurements on repeated imaging of the same individual also demonstrated that both CT methods produced more consistent measurements (ICC 0.986 for standard CT, 0.981 for 3D CT, 0.935 for XR).Conclusion
Although standard XR does provide a high level of reliability, it appears to slightly overestimate PI. CT scans do provide increased reliability, with no additional benefit of 3D reconstructions over standard CT.
... Sacral fractures were assessed systematically, and in accordance with the radiographic measurement techniques previously described for the evaluation of sacral fractures and morphology. [23][24][25][26] Measurements were completed on computed tomography images of the pelvis with picture archiving and communication system (PACS) software at each institution. Sacral measurements of primary interest included sagittal segmental kyphosis to measure the degree of angulation at the fracture site, and the sacral Cobb angle to assess global sacral morphology and alignment (Fig. 3). ...
Objectives:
Investigate the incidence of sacral dysmorphism (SD) in patients with spinopelvic dissociation (SPD).
Design:
Retrospective case series.
Setting:
Two academic level 1 trauma centers.
Patients/participants:
One thousand eight hundred fifty adult patients with sacral and pelvic fractures (OTA/AO 61-A, B, C).
Intervention:
Plain pelvic radiographs and CT scans.
Main outcome measurements:
Incidence of SD in patients with SPD. Secondary radiographic evaluation of fracture classification and deformity on sagittal imaging.
Results:
Eighty-two patients with SPD were identified, and 12.2% displayed features of SD, significantly less than reported in the literature. The S2 sacral body was the most common horizontal fracture location in patients with SD and nondysmorphic sacra (ND). Roy-Camille type I patterns were more common in ND (35%), versus type II in SD patients (40%). SD patients had lower body mass indexes (19.7 vs. 25.2, P = 0.001). Segmental kyphosis (22.5 degrees ND vs. 23.8 degrees SD, P = 0.838) and sacral kyphosis (26 degrees ND vs. 31 degrees SD, P = 0.605) were similar between groups. Percutaneous fixation was the most common surgical technique.
Conclusions:
We report a significantly lower prevalence of SD in patients with SPD than previously reported in the literature. This suggests that variations in sacral osseous anatomy alter force transmission across the sacrum during traumatic loading, which may be protective against certain high-energy fracture patterns. Preoperative evaluation of sacral anatomy is critical, not only in determining the size and orientation of sacral segment safe zones for screw placement, but also to better understand the pathomechanics involved in sacral trauma.
Level of evidence:
Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
... PI was defined as the angle between the line connecting the midpoint of the sacral plate to the center of the femoral head. PI value does not change during postural change 11 ; SS was defined as the angle between the sacral plate and the horizontal axis. The SS was regarded as the anatomic plane of the sagittal pelvic tilt in this study. ...
Purpose
Dislocation is a major complication after total hip arthroplasty (THA), and pelvic stiffness is reportedly a significant risk factor for dislocation. This study aimed to investigate spinopelvic alignment, and identify preoperative factors associated with postoperative pelvic mobility.
Methods
We enrolled 78 THA patients with unilateral osteoarthritis. The sagittal spinopelvic alignment in the standing and sitting position was measured using an EOS imaging system before and 3 months after THA. We evaluated postoperative pelvic mobility, and defined cases with less than 10° of sacral slope change as pelvic stiff type. The preoperative characteristics of those with postoperative stiff type, and preoperative factors associated with risk of postoperative stiff type were evaluated.
Results
Sagittal spinopelvic alignment except for lumbar alignment were significantly changed after THA.A total of 13 patients (17%) were identified as postoperative pelvic stiff type. Preoperative lower pelvic and lumbar mobility were determined as significant factors for prediction of postoperative pelvic stiff type. Among these patients, nine patients (69%) did not have pelvic stiffness before THA. Preoperative factor associated with the risk of postoperative pelvic stiff type in those without preoperative stiffness was lower lumbar lordosis in standing position by multivariate regression analysis.
Conclusion
Spinopelvic alignments except lumber alignment was significantly changed after THA. The lower pelvic mobility and lumbar alignment were identified as the preoperative predictive factors for postoperative pelvic mobility. Evaluation of preoperative lumbar alignment may be especially useful for the prediction in patients with hip contractures, for these patients may possibly experience the extensive perioperative change in pelvic mobility.
... Legaye et al. [9] demonstrated a strong positive correlation between PI and the age of subjects over 60 years. Previous studies described degeneration of paravertebral muscles in patients with spinal disease [10,11]. ...
Introduction
Sagittal balance and fatty infiltration of paraspinal muscle are important factors in patients with lumbar spinal stenosis (LSS) that may affect patients’ quality of life. Sagittal spinopelvic parameters and fatty infiltration may be associated with the severity of LSS. The purpose of this study was to test the hypothesis that severity of fatty infiltration correlates with severity of LSS and with sagittal pelvic alignment independent of age.
Methods
Age and body mass index (BMI) were extracted. Fatty infiltration was rated according to Goutallier classification and the severity of LSS was graded according to Schizas at five intervertebral disc levels. Overall fatty infiltration was computed as average fatty infiltration (aFI) and severity of LSS was defined as the highest severity of LSS of all segments. The sagittal spinopelvic parameters pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL) and PI-LL were measured. Associations among parameters were assessed using Spearman correlation coefficients adjusted for age (α = 0.05).
Results
165 LSS patients with a median age of 69 years were included. All parameters correlated with age (R>0.162, P<0.05) except BMI and LL (R<0.007, P>0.05). aFI correlated with PI, PT and PI-LL before (R>0.371, P<0.05) and after (R>0.180, P<0.05) adjusting for age. Severity of LSS correlated with PI, PT and PI-LL before (R>0.187, P<0.05) but not after (R<0.130, P>0.05) adjusting for age. aFI correlated with severity of LSS before (R=0.349, P<0.05) but not (R=0.114, P>0.05) after adjusting for age.
Conclusions
The correlation of aFI with sagittal spinopelvic parameters indicates that there might be a relationship between muscle characteristics and the sagittal alignment. Sagittal spinopelvic parameters and fatty infiltration of paraspinal muscles are not associated with radiological severity of LSS. Whether they are associated with clinical manifestation of LSS remains to be investigated.
... In contrast, we found that lower PIA patients may be a contributing factor to the development of ASD after long spinal fusion (Table 2). Many studies [32][33][34][35][36][37][38] have focused on how to correct the sagittal profile, including increased LLA, reduced normal C7 plumb line and PTA, but our results show that there was no significant significant difference between the incidence of ASD with preoperative and postoperative spinopelvic parameters, except for PIA. The PI, or pelvic base angle, is a useful descriptive terminology and an extremely important parameter for determining the global spinal balance of an individual [39,40]. ...
Purpose We investigated whether spinopelvic parameters are important prognostic factors for adjacent segment degeneration after long instrumented spinal fusion for degenerative spinal disease.
Methods This uncontrolled, randomized, single arm retrospective study included patients who underwent long instrumented lumbar fusion (fusion levels≥ 4) in the past 5 years with follow-up for at least 2 years. The inclusion criteria included adult patients (≥40 years of age) with a diagnosis of spinal degeneration who underwent instrumented corrective surgery. The exclusion criteria included preexisting adjacent disc degeneration, combined anterior reconstructive surgery, and distal ASD. Clinical and operative characters were evaluated. Lumbar lordotic angle (LLA), sacral slope angle (SSA), pelvic tilt angle (PTA) and pelvic incidence angle (PIA) were compared preoperatively, postoperatively and at the final follow-up.
Results From 2009 to 2014, 60 patients (30 ASD and 30 non-ASD patients) were enrolled. The average age was 66.82 ± 7.48 years for the study group and 67.97 ± 7.81 years for the control group. There was no statistically significant difference in clinical and operative characteristics. Among all spinopelvic parameters, only pre-, post-operative and final follow-up PIA in ASD group (53.9±10.4ﾟ, 54.6±14.0ﾟ, 54.3±14.1ﾟ) and non-ASD group (60.3±13.0ﾟ, 61.8±11.3ﾟ, 62.5±11.2ﾟ) showed statistically significant differences (p<0.05).
Conclusion This study confirms that preoperative, postoperative and final follow-up PIA is a significant factor contributing to the development of adjacent segment degeneration after long instrumented spinal fusion.
... As a result, the location of the C7 vertebral body was either corrected, in the case its bounding box was successfully detected, or statistically modeled by considering the location of other vertebral bodies, in the case its bounding box was not detected. 3. Variation in the shape of the sacral endplate The appearance and morphology of the sacral endplate, for example in the case of a dome-shaped sacrum [31], do not allow for an accurate assessment of its inclination. To tackle this problem, a line is regressed to the detected anterior corner, center point and posterior corner of the sacral endplate, therefore enabling a more robust determination of its inclination. ...
PurposeThe purpose of this study is to evaluate the performance of a novel deep learning (DL) tool for fully automated measurements of the sagittal spinopelvic balance from X-ray images of the spine in comparison with manual measurements.Methods
Ninety-seven conventional upright sagittal X-ray images from 55 subjects were retrospectively included in this study. Measurements of the parameters of the sagittal spinopelvic balance, i.e., the sacral slope (SS), pelvic tilt (PT), spinal tilt (ST), pelvic incidence (PI) and spinosacral angle (SSA), were obtained manually by identifying specific anatomical landmarks using the SurgiMap Spine software and by the fully automated DL tool. Statistical analysis was performed in terms of the mean absolute difference (MAD), standard deviation (SD) and Pearson correlation, while the paired t test was used to search for statistically significant differences between manual and automated measurements.ResultsThe differences between reference manual measurements and those obtained automatically by the DL tool were, respectively, for SS, PT, ST, PI and SSA, equal to 5.0° (3.4°), 2.7° (2.5°), 1.2° (1.2°), 5.5° (4.2°) and 5.0° (3.5°) in terms of MAD (SD), with a statistically significant corresponding Pearson correlation of 0.73, 0.90, 0.95, 0.81 and 0.71. No statistically significant differences were observed between the two types of measurement (p value always above 0.05).Conclusion
The differences between measurements are in the range of the observer variability of manual measurements, indicating that the DL tool can provide clinically equivalent measurements in terms of accuracy but superior measurements in terms of cost-effectiveness, reliability and reproducibility.
... The different finding maybe resulted from different diagnosis and operations. Many studies 25,[33][34][35][36][37][38] have focused on how to correct the sagittal profile, including increased LLA, reduced normal C7 plumb line and PTA, but our results showed that there was no significant significant difference between the incidence of ASD with the correction of all spinopelvic parameters (Table 3). Only preoperative, postoperative and follow-up PIA were responsible for the progression of ASD. ...
Background We investigated whether spinopelvic parameters are important prognostic factors causing adjacent segment degeneration (ASD) after long instrumented spinal fusion for degenerative spinal disease.
Methods This uncontrolled, randomized, single arm retrospective study included patients who underwent long instrumented lumbar fusion (fusion levels≥ 4) in the past 5 years with follow-up for at least 2 years. The inclusion criteria included adult patients (≥40 years of age) with a diagnosis of spinal degeneration who underwent instrumented corrective surgery. The exclusion criteria included preexisting adjacent disc degeneration, combined anterior reconstructive surgery, and distal ASD. Clinical and operative characters were evaluated. Angle of lumbar lordosis (LLA), sacral slope (SSA), pelvic tilt (PTA) and pelvic incidence (PIA) were compared preoperatively, postoperatively and at the final follow-up.
Results From 2009 to 2014, 60 patients (30 ASD and 30 non-ASD) were enrolled. The average age was 66.82 ± 7.48 years for the study group and 67.97 ± 7.81 years for the control group. There was no statistically significant difference in clinical and operative characteristics. Among all spinopelvic parameters, only pre-, post-operative and final follow-up PIA in ASD group (53.9±10.4ﾟ, 54.6±14.0ﾟ, 54.3±14.1ﾟ) and non-ASD group (60.3±13.0ﾟ, 61.8±11.3ﾟ, 62.5±11.2ﾟ) showed statistically significant differences ( p <0.05).
Conclusion This study confirms that preoperative, postoperative and final follow-up PIA is a significant factor contributing to the development of ASD after long instrumented spinal fusion.
... There are reciprocal changes in sacral slope (and lumbar lordosis), which maintains the body's center of gravity to within a few millimeters of the front of the sacrum when upright. 7,19,25 The normal pelvic tilt seen in our study was probably due to the maintenance of the balanced sagittal gravity line in this cohort without spinal pathology. ...
Background
Acetabular retroversion may lead to impingement and pain, which can be treated with an anteverting periacetabular osteotomy (aPAO). Pelvic tilt influences acetabular orientation; as pelvic tilt angle reduces, acetabular version reduces. Thus, acetabular retroversion may be a deformity secondary to abnormal pelvic tilt (functional retroversion) or an anatomic deformity of the acetabulum and the innominate bone (pelvic ring).
Purpose
To (1) measure the spinopelvic morphology in patients with acetabular retroversion and (2) assess whether pelvic tilt changes after successful anteverting PAO (aPAO), thus testing whether preoperative pelvic tilt was compensatory.
Study Design
Case series; Level of evidence, 4.
Methods
A consecutive cohort of 48 hips (42 patients; 30 ± 7 years [mean ± SD]) with acetabular retroversion that underwent successful aPAO was studied. Spinopelvic morphology (pelvic tilt, pelvic incidence, anterior pelvic plane, and sacral slope) was measured from computed tomography scans including the sacral end plate in 21 patients, with adequate images. In addition, the change in pelvic tilt with aPAO was measured via the sacrofemoral-pubic angle with supine pelvic radiographs at an interval of 2.5 ± 2 years.
Results
The spinopelvic characteristics included a pelvic tilt of 4° ± 4°, a sacral slope of 39° ± 9°, an anterior pelvic plane angle of 11° ± 5°, and a pelvic incidence of 42° ± 10°. Preoperative pelvic tilt was 4° ± 4° and did not change postoperatively (4° ± 4°) ( P = .676).
Conclusion
Pelvic tilt in acetabular retroversion was within normal parameters, illustrating “normal” sagittal pelvic balance and values similar to those reported in the literature in healthy subjects. In addition, it did not change after aPAO. Thus, acetabular retroversion was not secondary to a maladaptive pelvic tilt (functional retroversion). Further work is required to assess whether retroversion is a reflection of a pelvic morphological abnormality rather than an isolated acetabular abnormality. Treatment of acetabular retroversion should focus on correcting the deformity rather than attempting to change the functional pelvic position.
... It is noted that an individual's pelvic morphology can dictate a unique and customization from 'ideal' lumbo-thoracic curves 26) , however, since the pelvic incidence for this patient was within normal limits (58° vs. 43 to 62° normal 27) ), the usual normative parameters were considered adequate for comparison [22][23][24] . Further, due to the patient's age and thoracic hyperkyphosis, we evaluated the thoracic spine closely. ...
[Purpose] To present the dramatic improvement of sagittal posture in a young male with Scheuermann’s disease suffering from pain ailments as treated by Chiropractic BioPhysics® technique. [Participant and Methods] An 18 year old reported low back pain and headaches for several years. Full spine radiographic assessment revealed pronounced thoracic hyperkyphosis, anterior head translation, posterior thoracolumbar sagittal balance, and a reduced sacral base orientation. The patient was treated by Chiropractic BioPhysics methods incorporating mirror image® exercises, traction, as well as spinal manipulation. [Results] Assessment after 35 treatment sessions over 14-weeks revealed a dramatic improvement in postural parameters. The thoracic kyphosis reduced by 13°, and was accompanied by a reduction in forward head posture, reduction in posterior sagittal balance, and an increase in sacral base angle to normal. The low back pain and headaches were alleviated. [Conclusion] This case adds to the accumulating evidence demonstrating CBP methods offers an effective approach to reduce the burden of postural disorders including those with Scheuermann’s disease. Since thoracic hyperkyphosis is a serious disorder, the routine comprehensive assessment via full-spine radiography is essential for the quantification of relevant postural parameters.
... However, our results for the standing position were very small, although there were statistical differences post-treatment for the dry needling group in ROF and ROEF only (34). With respect to asymptomatic adults, our data were lower, considering that the normal range of value for the sacral slope is from -32º to -49º (35,36). Several studies using skin-surface devices have established normal values for sagittal curvature of the thoracic spine. ...
BACKGROUND: The etiology of fibromyalgia syndrome (FMS) is inconclusive, but central mechanisms are well accepted for this pain condition. Myofascial pain syndrome (MPS) is one of the most common musculoskeletal pain diseases and is characterized by myofascial trigger points (MTrPs). It has been suggest that MTrPs have an important factor in the genesis of FMS.
OBJECTIVE: The purpose of the current randomized clinical trial was to compare the effectiveness of dry needling versus cross tape on spinal mobility and MTrPs in spinal muscles in patients with FMS.
STUDY DESIGN: A single-blind randomized controlled trial was conducted on patients with FMS.
SETTING: Clinical setting.
METHODS: Sixty-four patients with FMS were randomly assigned to an experimental group receiving dry needling therapy or to a control group for cross tape therapy in the MTrPs in the latissimus dorsi, iliocostalis, multifidus, and quadratus lumbourum muscles. Spinal mobility measures and MTrPs algometry were recorded at baseline and after 5 weeks of treatment.
RESULTS: The repeated measures analysis of variance (ANOVA) demonstrated that significant differences between groups were achieved for the MTrPs in latissimus dorsi muscle (right axillary portion: F = 9.80, P = 0.003); multifidus muscle (right L2 level: F = 11.80, P = 0.001); quadratus lumborum (right lateral superficial upper: F = 6.67, P = 0.012; and right lateral superficial lower: F = 5.38, P = 0.024). In addition, the ANOVA repeated measures test showed significant differences between groups for the segmental amplitude thoracic spine in the standing erect position (F = 7.33, P = 0.009), and segmental amplitude of lumbar spine (F = 11.60, P = 0.001) in the sitting erect position.
LIMITATIONS: The outcomes were not collected from a long-term follow-up period. Dry needling therapy or cross tape were used alone when in reality physical therapists usually treat patients with FMS using a multi-modal approach. A non-treatment control group was not included.
CONCLUSIONS: This study has demonstrated that dry needling therapy reduces myofacial trigger points algometry on thoracic and lumbar muscles. Dry needling and cross tape approaches reported a similar effect size for spinal mobility measures in patients with FMS.
... Both the pelvic incidence and sacral anatomical orientation of Kebara 2 indicate a position of the sacrum that is 20-22°less than that of modern humans (Table 18.1). Given that, the sacral endplate of modern humans is aligned at an angle of 39-41°to the horizontal plane (Boulay et al. 2006;Legaye 2007;Peleg et al. 2007; Mac-Thiong 2010), we aligned the sacrum of Kebara 2 at 21°to the horizontal plane ( Fig. 18.3). ...
Spinal posture has vast biomechanical
, locomotor and pathological implications in hominins
. Assessing the curvatures of the spine of fossil hominins can provide important information towards the understanding of their paleobiology. Unfortunately, complete hominin spines are very rarely preserved in the fossil record. The Neanderthal partial skeleton, Kebara 2 from Israel, constitutes a remarkable exception, representing an almost complete spine and pelvis. The aim of this study is, therefore, to create a new 3D virtual reconstruction of the spine of Kebara 2. To build the model, we used the CT scans of the sacrum, lumbar and thoracic vertebrae of Kebara 2, captured its 3D morphology, and, using visualization software (Amira 5.2©), aligned the 3D reconstruction of the original bones into the spinal curvature. First we aligned the sacrum and then we added one vertebra at a time, until the complete spine (T1-S5) was intact. The amount of spinal curvature (lordosis
and kyphosis), the sacral orientation, and the coronal plane deviation was determined based on the current literature or measured and calculated specifically for this study based on published methods. This reconstruction provides, for the first time, a complete 3D virtual reconstruction of the spine of an extinct hominin. The spinal posture and spinopelvic alignment of Kebara 2 show a unique configuration compared with that of modern humans, suggesting locomotor and weight-bearing differences between the two. The spinal posture of Kebara 2 also shows slight asymmetry in the coronal plane. Stature estimation of Kebara 2 based on spinal length confirms that the height of Kebara 2 was around 170 cm. This reconstruction can now serve as the basis for a more complete reconstruction of the Kebara 2
specimen, which will include other parts of this remarkable fossil, such as the pelvis, the rib cage and the cervical spine.
... As a most commonly used spinopelvic parameter, pelvic incidence (PI) was first described by Duval-Beaupere et al. [1] to evaluate the sagittal alignment of pelvis. Additionally, pelvic morphology (PR-S1 angle) [2] and the femoro-sacral posterior angle (FSPA) [3] were presented to serve as alternative morphologic pelvic parameters of PI in patients with a dome-shaped deformity of the sacrum. Considering that the upper edge of the pubic symphysis was easy to identify on the lateral X-ray film, Wang et al. [4] took it as an alternative landmark of the hip axis and proposed two morphologic parameters: the sacrum pubic incidence (SPI) and sacrum pubic posterior angle (SPPA). ...
Background
Recently, a grayscale inversion view was reported to improve intra- and inter-observer reliabilities in measuring coronal curvature with Cobb and pedicle methods in scoliosis patients. However, the grayscale transformation has never been applied to the measurements of spinopelvic parameters. The purpose of this study was to compare the measurement reliabilities of the spinoplevic sagittal parameters between the ‘Standard View’ and the ‘Grayscale Inversion View’ in normal adult populations.
Methods
A total of 30 asymptomatic subjects aged between 30 and 40 years were included in this study. Whole-spine posteroanterior radiographs were used to measure the spinoplevic sagittal parameters including thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), sacral slope (SS) and pelvic tilt (PT) in both standard view and grayscale inversion view. Two independent observers measured the parameters twice at a 2-week interval. Intra- and inter-observer reliabilities were compared between the two radiographic views. The absolute differences between the two sets of measurements on each view were calculated and compared.
Results
The intra-class correlation coefficients (ICCs) of PI, PT and SVA were greater in the grayscale inversion view than in the standard view (0.972 vs 0.817, 0.937 vs 0.833 and 0.964 vs 0.901 for observer 1, respectively; 0.990 vs 0.826, 0.995 vs 0.842 and 0.969 vs 0.919 for observer 2, respectively). Overall, the improvement of ICC was greater in parameters of sagittal pelvic alignment than in those of sagittal spinal alignment. As for the mean absolute differences between two measurements, significant differences existed between the two views in terms of PI, PT and SVA (p = 0.014, 0.016 and 0.011 for observer 1, respectively; p = 0.014, 0.025 and 0.046 for observer 2, respectively).
Conclusions
A grayscale inversion view provided improved intra- and inter-observer reliabilities in measuring spinoplevic alignment when compared with a standard view. This view was more useful in subjects whose pelvic anatomical structures can’t be identified clearly on the standard X-ray view.
... These included anterior-posterior and horizontal displacement measured on axial MDCT images, vertical displacement measured on coronal MDCT images, and anterior-posterior translation and kyphotic segmental angulation measured on sagittal MDCT images. To assess the sagittal alignment of the sacrum, the sacral table angle, global sacral kyphosis using the Cobb method, and pelvic incidence were measured [21][22][23][24]. ...
The objective of the present study is to evaluate multidetector computed tomographic (MDCT) fracture patterns and associated injuries in patients with spinopelvic dissociation (SPD). Our institutional trauma registry database was reviewed from Jan. 1, 2006, to Sept. 30, 2012, specifically evaluating patients with sacral fractures. MDCT scans of patients with sacral fractures were reviewed to determine the presence of SPD. SPD cases were characterized into the following fracture patterns: U-shaped, Y-shaped, T-shaped, H-shaped, and burst. The following MDCT features were recorded: level of the horizontal fracture, location of vertical fracture, kyphosis between major fracture fragments, displacement of fracture fragment, narrowing of central spinal canal, narrowing of neural foramina, and extension into sacroiliac joints. Quantitative evaluation of the sacral fractures was performed in accordance with the consensus statement by the Spine Trauma Study Group. Medical records were reviewed to determine associated pelvic and non-pelvic fractures, bladder and bowel injuries, nerve injuries, and type of surgical intervention. Twenty-one patients had SPD, of whom 13 were men and eight were women. Mean age was 41.8 years (range 18.8 to 87.7). Five fractures (24 %) were U-shaped, six (29 %) H-shaped, four (19 %) Y-shaped, and six (29 %) burst. Nine patients (43 %) had central canal narrowing, and 19 (90 %) had neural foramina narrowing. Eleven patients (52 %) had kyphotic angulation between major fracture fragments, and seven patients (33 %) had either anterior (24 %) or posterior (10 %) displacement of the proximal fracture fragment. Fourteen patients (67 %) had associated pelvic fractures, and 20 (95 %) had associated non-pelvic fractures. Two patients (10 %) had associated urethral injuries, and one (5 %) had an associated colon injury. Seven patients (33 %) had associated nerve injuries. Six patients (29 %) had surgical fixation while 15 (71 %) were managed non-operatively. On trauma MDCT examinations, patients with SPD have characteristic fracture patterns. It is important to differentiate SPD from other pelvic ring injuries due to high rate of associated injuries. Although all SPD injuries are unstable and need fixation, the decision for operative management in an individual patient depends on the systemic injury pattern, specific fracture pattern, and the ability to attain stable screw fixation.
... Pelvic parameters, namely PI, have been shown to be significantly higher for subjects with spondylolis-thesis, 13,15,16,[38][39][40] and in spondylolysis. 40,41 A recent review 42 showed that pelvic incidence had been concluded as a predictive factor for spondylolisthesis in some of the published literature. 13,15,39 It had also reported that few studies showed no significant difference between PI of normal and subjects with scoliosis. ...
Rib-based and spine-based systems are commonly used distraction-based growth friendly treatments for early-onset scoliosis (EOS). Our primary purpose was to determine the risk of developing postoperative proximal junctional kyphosis (PJK) during distraction-based growth friendly surgery.
A multicenter, retrospective, radiographic comparison was performed for a group of 40 children with EOS who were treated with posterior distraction-based implants. PJK was defined as proximal junction sagittal angle (PJA)≥10 degrees and PJA at least 10 degrees greater than preoperative.
Eight subjects (20%) at immediate postoperative follow-up and 11 subjects (27.5%) at minimum 2-year follow-up had developed PJK. The risk of developing PJK between rib-based and spine-based growing systems was not significantly different at immediate postoperative (17% vs. 25%) or at final (25% vs. 31%) follow-ups.Further analysis combining both treatment groups demonstrated that PJK subjects were significantly older at time of initial surgery (7.1 y PJK vs. 5.0 y no PJK). Radiographic comparisons between PJK versus no PJK: Preoperative scoliosis (69.9 vs. 76.0 degrees), thoracic kyphosis (45.1 vs. 28.7 degrees), lumbar lordosis (53.1 vs. 44.0 degrees), PJA (2.2 vs. 2.8 degrees), sagittal vertical axis (1.5 vs. 2.6 cm), pelvic incidence (52.8 vs. 47.4 degrees), pelvic tilt (14.3 vs. 8.7 degrees), and sacral slope (37.7 vs. 35.9 degrees). At both initial postoperative and at final follow-up visits, a significant difference was found for cervical lordosis 32.2 versus 14.0 degrees and 42.0 versus 16.6 degrees, respectively. Risk ratio for developing PJK at final follow-up was 2.8 for subjects with preoperative thoracic hyperkyphosis and was 3.1 for subjects with high pelvic incidence (P<0.05).
The risk of developing PJK during distraction-based growth friendly treatment for EOS was 20% immediately after implantation and 28% at minimum 2-year follow-up, with no difference observed between rib-based and spine-based treatment groups. As this study identifies a significant risk of developing PJK during the treatment of EOS, it allows clinicians to preoperatively council patients and their families about this possible complication. In addition, several potential risk factors for the development of postoperative PJK were identified, but should be investigated further in future studies.
Level III-therapeutic study (retrospective, comparative).
... EOS 2D/3D system in the assessment of idiopathic scoliosis EOS 2D system It can be used to determine the usual spinal and pelvic radiographic parameters in both the coronal and sagittal planes (Table 1), and to assess skeletal maturity [27][28][29][30][31][32][33][34]. According to the Lenke classification system (Table 2), different types of scoliosis may be encountered (Figs. ...
Idiopathic scoliosis is one of the most common conditions encountered in paediatric practice. It is a three-dimensional (3D) spinal deformity. Conventional radiography is still the modality of choice for evaluation of children and adolescents with idiopathic scoliosis, but it requires repeat radiographs until skeletal maturity is reached and does not provide information about spinal deformity in all three planes. A biplanar X-ray device is a new technique that enables standing frontal and lateral radiographs of the spine to be obtained at lowered radiation doses. With its specific software, this novel vertical biplanar X-ray unit provides 3D images of the spine and offers the opportunity of visualising the spinal deformity in all three planes. This pictorial review presents our experience with this new imaging system in children and adolescents with idiopathic scoliosis.
Key Points
• The biplanar X-ray device produces two orthogonal spine X-ray images in a standing position.
• The biplanar X-ray device can assess idiopathic scoliosis with a lower radiation dose.
• The biplanar X-ray device provides 3D images of the spine.
Spinal measurements play an integral role in surgical planning for a variety of spine procedures. Full-length imaging eliminates distortions that can occur with stitched images. However, these images take radiologists significantly longer to read than conventional radiographs. Artificial intelligence (AI) image analysis software that can make such measurements quickly and reliably would be advantageous to surgeons, radiologists, and the entire health system.
Institutional Review Board approval was obtained for this study. Preoperative full-length standing anterior–posterior and lateral radiographs of patients that were previously measured by fellowship-trained spine surgeons at our institution were obtained. The measurements included lumbar lordosis (LL), greatest coronal Cobb angle (GCC), pelvic incidence (PI), coronal balance (CB), and T1-pelvic angle (T1PA). Inter-rater intra-class correlation (ICC) values were calculated based on an overlapping sample of 10 patients measured by surgeons. Full-length standing radiographs of an additional 100 patients were provided for AI software training. The AI algorithm then measured the radiographs and ICC values were calculated.
ICC values for inter-rater reliability between surgeons were excellent and calculated to 0.97 for LL (95% CI 0.88–0.99), 0.78 (0.33–0.94) for GCC, 0.86 (0.55–0.96) for PI, 0.99 for CB (0.93–0.99), and 0.95 for T1PA (0.82–0.99). The algorithm computed the five selected parameters with ICC values between 0.70 and 0.94, indicating excellent reliability. Exemplary for the comparison of AI and surgeons, the ICC for LL was 0.88 (95% CI 0.83–0.92) and 0.93 for CB (0.90–0.95). GCC, PI, and T1PA could be determined with ICC values of 0.81 (0.69–0.87), 0.70 (0.60–0.78), and 0.94 (0.91–0.96) respectively.
The AI algorithm presented here demonstrates excellent reliability for most of the parameters and good reliability for PI, with ICC values corresponding to measurements conducted by experienced surgeons. In future, it may facilitate the analysis of large data sets and aid physicians in diagnostics, pre-operative planning, and post-operative quality control.
Purpose: We investigated the relationships between patient factors, including obesity, osteopenia, and scoliosis, and the reliability of measures of the spinopelvic sagittal parameters using conventional X-radiography (Xp) and slot-scanning Xp devices (EOS) and examined the differences in interobserver measurement reliability between them.
Methods: We retrospectively enrolled 55 patients (52.7 ± 25.3 years, 27 females) with conventional whole-spine Xp and EOS images taken within three months. Patients were classified according to obesity (Body mass index ≥ 25 kg/m²), osteopenia (T score < −1), and scoliosis (Cobb angle > 20°). The associations between patient factors and reliability of radiological parameter measurements were examined with interobserver intraclass correlation coefficient (ICC), defined as poor, <.40; good, 40–.79; and excellent, ≥.80.
Results: All parameters measured with EOS showed excellent reliability except for L4-S (ICC:.760, 95% CI:.295–.927) in the obesity+ group. All parameters measured with conventional Xp were excellent except for those classified as good: L4-S (.608,.093–.868) and pelvic incidence (PI) (.512,.078–.832) in the obese+ group; T1 slope (.781,.237–.952), L4-S (.718,.112–.936), sacral slope (SS) (.792,.237–.955), pelvic tilt (PT) (.787,.300–.952), and center of acoustic meatus and femoral head offset (CAM-HA) (.690,.090–.928) in the osteopenia+ group; and lumbar lordosis (LL, L4-S) (.712,.349–.889), SS (.608,.178–.843), and CAM-HA (.781,.480–.917) in the scoliosis+ group.
Conclusion: Reliability of EOS measurements was preferable except for L4-S in patients with obesity. The reliability of conventional Xp measurements of pelvic parameters SS, PT, and PI was affected by patient factors, including obesity, osteopenia, and scoliosis. When evaluating lower lumbar and pelvic parameters in patients with these factors, we recommend substituting thoracic parameters, LL (L1-S), sagittal vertical axis (SVA), and T1 pelvic angle (TPA), or combining computed tomography (CT) measurements.
Background:
According to previous studies, the relationship between lumbar lordosis and thoracic kyphosis or that between pelvic parameters and thoracic kyphosis have been inconsistent.
Objective:
The purpose of this study was to investigate spinal sagittal alignment and its relationship to global and regional lumbar and thoracic angles, pelvic and sway angles, and C7-S1 distance measurements, followed by a detailed subgroup analysis using an inertial measurement unit system.
Methods:
A total of 51 asymptomatic volunteers stood in a comfortable posture with inertial measurement units attached to the T1, T7, T12, L3, and S2 vertebrae. T1, T7, T12, L3, and S2 sagittal angles were acquired during standing posture using the Eulerian angle coordinate system. All angles are reported as the mean of three 5-s measurements. Following the measurement of lumbar lordosis angles (T12 relative S2), participants were divided into the flat lumbar and normal lordosis groups.
Results:
There were different correlation patterns between groups because of spinal sagittal imbalance, which was greater in the flat lumbar group than in the normal lordosis group. In addition, sacral inclination proved the ideal parameter to evaluate reciprocal balance in lumbar lordosis, showing a stronger correlation with lower than with upper lumbar lordosis. T1 was the key element in assessing thoracic kyphosis, which showed a stronger correlation with upper than with lower thoracic kyphosis.
Conclusion:
We suggest that when assessing posture, it is necessary to identify the global and regional angles and it is useful to classify spinal sagittal alignment into subgroups according to lumbar lordosis and evaluate the groups separately.
Background:
Pelvic incidence (PI) and Jackson's angle are two major spinopelvic parameters that define the position of the sacrum within the pelvis. These parameters are measured on standing lateral radiography, and the identification of the hip axis is essential for measurements. Moreover, identifying the hip axis in patients with hip diseases or femoral head deformity is challenging. In this study, we described a novel parameter named posterior pubic incidence (PPI) that could be measured using the posterior pubic edge instead of the hip axis.
Methods:
Group A comprised 50 volunteers who underwent standing lateral lumbosacral radiography. Group B comprised 54 patients with abdominal or urologic problems who underwent supine computed tomography (CT). The PI, pelvic tilt (PT), sacral slope (SS), PPI, and posterior pubic tilt (PPT) were measured. The differences between PI and PPI were evaluated. Linear regression analysis was used to predict the PI value from PPI.
Results:
The mean PI and PPI values were 47.41° ± 12.32° and 49.32° ± 11.94° in Group A and 49.19° ± 9.99° and 49.99° ± 9.25° in Group B, respectively. The mean absolute differences in Groups A and B were 2.41° ± 1.63° and 1.9° ± 1.62°, respectively. High correlations were obtained between PI/PPI and PT/PPT. PI could be calculated as PI° = PPI° - 2° on plain radiography and as PI° = PPI° - 1° on CT.
Conclusion:
PPI was strongly correlated with PI, was nearly equal to PI, and may replace PI in formulas containing PI.
Background
Assessment of spine alignment is crucial in the management of scoliosis, but current auto-analysis of spine alignment suffers from low accuracy. We aim to develop and validate a hybrid model named SpineHRNet+, which integrates artificial intelligence (AI) and rule-based methods to improve auto-alignment reliability and interpretability.
Methods
From December 2019 to November 2020, 1,542 consecutive patients with scoliosis attending two local scoliosis clinics (The Duchess of Kent Children's Hospital at Sandy Bay in Hong Kong; Queen Mary Hospital in Pok Fu Lam on Hong Kong Island) were recruited. The biplanar radiographs of each patient were collected with our medical machine EOS™. The collected radiographs were recaptured using smartphones or screenshots, with deidentified images securely stored. Manually labelled landmarks and alignment parameters by a spine surgeon were considered as ground truth (GT). The data were split 8:2 to train and internally test SpineHRNet+, respectively. This was followed by a prospective validation on another 337 patients. Quantitative analyses of landmark predictions were conducted, and reliabilities of auto-alignment were assessed using linear regression and Bland-Altman plots. Deformity severity and sagittal abnormality classifications were evaluated by confusion matrices.
Findings
SpineHRNet+ achieved accurate landmark detection with mean Euclidean distance errors of 2·78 and 5·52 pixels on posteroanterior and lateral radiographs, respectively. The mean angle errors between predictions and GT were 3·18° and 6·32° coronally and sagittally. All predicted alignments were strongly correlated with GT (p < 0·001, R² > 0·97), with minimal overall difference visualised via Bland-Altman plots. For curve detections, 95·7% sensitivity and 88·1% specificity was achieved, and for severity classification, 88·6–90·8% sensitivity was obtained. For sagittal abnormalities, greater than 85·2–88·9% specificity and sensitivity were achieved.
Interpretation
The auto-analysis provided by SpineHRNet+ was reliable and continuous and it might offer the potential to assist clinical work and facilitate large-scale clinical studies.
Funding
RGC Research Impact Fund (R5017–18F), Innovation and Technology Fund (ITS/404/18), and the AOSpine East Asia Fund (AOSEA(R)2019–06).
Background
Assessment of spine alignment is crucial in the management of scoliosis, but current auto-analysis of spine alignment suffers from low accuracy. We aim to develop and validate a hybrid model named SpineHRNet+, which integrates artificial intelligence (AI) and rule-based methods to improve auto-alignment reliability and interpretability.
Methods
From December 2019 to November 2020, 1,542 consecutive patients with scoliosis attending two local scoliosis clinics (The Duchess of Kent Children's Hospital at Sandy Bay in Hong Kong; Queen Mary Hospital in Pok Fu Lam on Hong Kong Island) were recruited. The biplanar radiographs of each patient were collected with our medical machine EOS™. The collected radiographs were recaptured using smartphones or screenshots, with deidentified images securely stored. Manually labelled landmarks and alignment parameters by a spine surgeon were considered as ground truth (GT). The data were split 8:2 to train and internally test SpineHRNet+, respectively. This was followed by a prospective validation on another 337 patients. Quantitative analyses of landmark predictions were conducted, and reliabilities of auto-alignment were assessed using linear regression and Bland-Altman plots. Deformity severity and sagittal abnormality classifications were evaluated by confusion matrices.
Findings
SpineHRNet+ achieved accurate landmark detection with mean Euclidean distance errors of 2·78 and 5·52 pixels on posteroanterior and lateral radiographs, respectively. The mean angle errors between predictions and GT were 3·18° and 6·32° coronally and sagittally. All predicted alignments were strongly correlated with GT (p < 0·001, R2 > 0·97), with minimal overall difference visualised via Bland-Altman plots. For curve detections, 95·7% sensitivity and 88·1% specificity was achieved, and for severity classification, 88·6–90·8% sensitivity was obtained. For sagittal abnormalities, greater than 85·2–88·9% specificity and sensitivity were achieved.
Interpretation
The auto-analysis provided by SpineHRNet+ was reliable and continuous and it might offer the potential to assist clinical work and facilitate large-scale clinical studies.
Funding
RGC Research Impact Fund (R5017–18F), Innovation and Technology Fund (ITS/404/18), and the AOSpine East Asia Fund (AOSEA(R)2019–06).
Preservation is a major obstacle in paleoanthropological studies. Since 1990s virtual methods have become an important part of anthropological research helping to overcome preservation problems in two principle ways: they improve extraction of information from a fragmentary material, and they permit a more objective reconstruction of fragmentary and incomplete remains. This thesis has focused on the virtual reconstruction of two fossil specimens: the modern human cranium from the Upper Paleolithic site of Zlatý kůň (ZK; Czech Republic) and the Neandertal Regourdou 1 (R1) pelvis (France). The reconstruction of the ZK cranium allowed us to revise sex attribution and analyze morphological affinity. Based on the secondary sex diagnosis, the ZK individual was most probably a female and exhibits a great affinity to Early Upper Paleolithic population. The R1 pelvis shows considerable asymmetry that was first analyzed on the sacrum in comparison with healthy modern humans and Neandertals. The asymmetry exceeds normal variation observed in the extant population and could have related to asymmetrical load dissipation. Therefore, the asymmetry was considered in the subsequent preliminary pelvic reconstruction which allowed us to assess sex of the individual and to analyze transverse dimensions of the pelvic canal and orientation of the sacrum in the pelvis. Based on the newly available sexually dimorphic traits, the R1 individual was probably a male. Transverse canal diameters indicate slightly wider outlet than in modern males, but they show similar relationship as in other archaic humans. Regarding the high degree of correlation between sacral orientation and lumbar lordosis, R1 had slightly higher lumbar lordosis angle (close to modern mean) than has been proposed for most of other Neandertals. This slightly extends the previously suggested Neandertal range of variation, which, however, still remains in the lower portion of modern human variation. In other presented studies, we focused on sex estimation from fragmentary remains and compatibility of 3D data digitization techniques. Specifically, we proposed a method for sex estimation from the posterior ilium and adjusted the visual method of Brůžek (2002) to the use on fragmentary material. Finally, we compared two different 3D scanners and their outcomes. They did not significantly differ with regard to subsequent anthropological analyses (sex and age estimation), but they may provide differential results in highly structured areas.
Objective: The purpose of this study is to perform analysis through the low back pain open data set to predict the incidence of non-specific chronic low back pain (NSLBP) to obtain a more accurate and convenient sagittal spinopelvic parameter model. Methods: The logistic regression analysis and multilayer perceptron(MLP) algorithm is used to construct a NSLBP prediction model based on the parameters of the spinopelvic parameters from open data source. Results: Degree of spondylolisthesis(DS), Pelvic radius (PR), Sacral slope (SS), Pelvic tilt (PT) are four predictors screened out by regression analysis that have significant predictive power for the risk of NSLBP. The overall accuracy of the equation prediction model is 85.8%.The MLP network algorithm determines that DS is the most powerful predictor of NSLBP through more precise modeling. The model has good predictive ability of 95.2% of accuracy. Conclusions: MLP models play a more accurate role in the construction of predictive models. Computer science is playing a greater role in helping precision medicine clinical research.
It is uncommon to get lumbosacral junction deformity due to tuberculosis. Lumbosacral junction alignment is of paramount importance in maintaining global sagittal balance. In this case report, we present a case of a 42-year-old woman with multidrug-resistant tuberculosis of lumbosacral spine with complete destruction of L3, L4 and L5 vertebra with partial destruction of L2 and S1 vertebra leading to significant shortening and lumbosacral kyphosis. The patient had severe axial low back pain, inability to sleep in supine position due to deformity and difficulty in walking due to loss of spinal alignment. The patient was treated with 6 weeks of antituberculous drugs followed by all posterior decompression with instrumentation from D10 to S2 with a reconstruction of anterior vertebral bodies with the help of an expandable cage. Antituberculous treatment was continued for 18 months. At present, the patient is asymptomatic with no neurological deficit and has completed 3.5 years of regular follow-up.
Aims:
The aims of this study were to measure sagittal standing and sitting lumbar-pelvic-femoral alignment in patients before and following total hip arthroplasty (THA), and to consider what preoperative factors may influence a change in postoperative pelvic position.
Patients and methods:
A total of 161 patients were considered for inclusion. Patients had a mean age of the remaining 61 years (sd 11) with a mean body mass index (BMI) of 28 kg/m2 (sd 6). Of the 161 patients, 82 were male (51%). We excluded 17 patients (11%) with spinal conditions known to affect lumbar mobility as well as the rotational axis of the spine. Standing and sitting spine-to-lower-limb radiographs were taken of the remaining 144 patients before and one year following THA. Spinopelvic alignment measurements, including sacral slope, lumbar lordosis, and pelvic incidence, were measured. These angles were used to calculate lumbar spine flexion and femoroacetabular hip flexion from a standing to sitting position. A radiographic scoring system was used to identify those patients in the series who had lumbar degenerative disc disease (DDD) and compare spinopelvic parameters between those patients with DDD (n = 38) and those who did not (n = 106).
Results:
Following THA, patients sat with more anterior pelvic tilt (mean increased sacral slope 18° preoperatively versus 23° postoperatively; p = 0.001) and more lumbar lordosis (mean 28° preoperatively versus 35° postoperatively; p = 0.001). Preoperative change in sacral slope from standing to sitting (p = 0.03) and the absence of DDD (p = 0.001) correlated to an increased change in postoperative sitting pelvic alignment.
Conclusion:
Sitting lumbar-pelvic-femoral alignment following THA may be driven by hip arthritis and/or spinal deformity. Patients with DDD and fixed spinopelvic alignment have a predictable pelvic position one year following THA. Patients with normal spines have less predictable postoperative pelvic position, which is likely to be driven by hip stiffness. Cite this article: Bone Joint J 2018;100-B:1289-96.
Background:
This case series of consecutive patients evaluated sagittal balance and health-related quality of life (HRQoL) 3 decades after in situ arthrodesis for high-grade isthmic spondylolisthesis.
Methods:
Global sagittal balance, pelvic parameters, and compensatory mechanisms were evaluated on standing lateral radiographs of the spine and pelvis for 28 of 39 consecutive patients, 28 to 41 years after in situ arthrodesis for high-grade L5 to S1 spondylolisthesis. The mean age at surgery was 14 years (range, 9 to 24 years), and the mean age at the time of follow-up was 48 years (range, 39 to 59 years). A subset of the radiographic parameters was compared with the corresponding data from an 8-year follow-up examination of the same patients. HRQoL was evaluated with the Scoliosis Research Society (SRS)-22r questionnaire.
Results:
We found that 3 of the 28 patients had a global sagittal imbalance (T1 spinopelvic inclination of >0°). Signs of compensatory mechanisms, such as reduced thoracic kyphosis and pelvic retroversion, were frequent. There was a significant decrease in sacral slope compared with 8-year follow-up data (p = 0.01). The median SRS-22r subscore was on the same level as Swedish normative data. We found no association between radiographic parameters and SRS-22r outcome.
Conclusions:
Three decades after in situ arthrodesis for high-grade spondylolisthesis, radiographic signs of noncompensated sagittal imbalance were observed in only a few individuals. The patients had normal SRS-22r scores. There was no association between any radiographic parameter and SRS-22r outcome. The findings are relevant in the controversial discussion on whether to perform a reduction procedure to treat high-grade spondylolisthesis.
Level of evidence:
Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Objectives:
Sagittal alignment of the lumbosacral spine, and specifically pelvic incidence (PI), has been implicated in the development of spine pathology, but generally ignored with regards to diseases of the hip. We aimed to determine if increased PI is correlated with higher rates of hip osteoarthritis (HOA). The effect of PI on the development of knee osteoarthritis (KOA) was used as a negative control.
Methods:
We studied 400 well-preserved cadaveric skeletons ranging from 50 to 79 years of age at death. Each specimen's OA of the hip and knee were graded using a previously described method. PI was measured from standardised lateral photographs of reconstructed pelvises. Multiple regression analysis was performed to determine the relationship between age and PI with HOA and KOA.
Results:
The mean age was 60.2 years (standard deviation (sd) 8.1), and the mean PI was 46.7° (sd 10.7°). Multiple regression analysis demonstrated a significant correlation between increased PI and HOA (standardised beta = 0.103, p = 0.017). There was no correlation between PI and KOA (standardised beta = 0.003, p = 0.912).
Conclusion:
Higher PI in the younger individual may contribute to the development of HOA in later life.Cite this article: Dr J. J. Gebhart. Relationship between pelvic incidence and osteoarthritis of the hip. Bone Joint Res 2016;5:66-72. DOI: 10.1302/2046-3758.52.2000552.
Back pain is one of the first causes of surgical intervention in the world and instrumentation is needed for about 1 patient out of 100 . Fusion is the gold standard for instrumented surgery and consists in fixation of two adjacent vertebra together with pedicular screws and rigid rods. Clinical outcomes of fusion are satisfactory but some cases of adverse events remain such as adjacent segment degeneration sometimes leading to revision surgery. Dynamic stabilization devices have been proposed to tackle this issue with the objective of maintaining motion at the instrumented level and thus limiting the surrounding structure overloading. This work aims at assessing one dynamic stabilization device. We first performed mechanical testing on the device to better understand its functioning and come up with a detailed and validated model. Then a retrospective clinical work has been conducted to lay out the clinical performances of the device and propose a prospective study design to answer clinical and scientific requirements. A biomechanical in-vitro testing campaign has been set up to increase our knowledge about the behaviour of the instrumented spine. This enabled us to validate a finite elements model then used for the study of the influence of several design parameters but also of several choices made during the surgery.
Study design::
Systematic Medline review.
Objective::
Overview of pedicle-based dynamic stabilization (PBDS) devices clinical outcomes.
Summary of background data::
Fusion is the standard instrumentation for many pathologies of the lumbar spine. Worrying rates of failure, including adjacent segment degeneration (ASD), have consistently been reported. The interest for dynamic stabilization came from the need of minimizing the long term complications related to the restriction of lumbar motion. However, PBDS advantages and drawbacks remain controversial.
Methods::
Articles about clinical outcomes were identified by a comprehensive Medline search. Inclusion criteria were a minimum follow-up of 12 M, indications for lumbar dynamic stabilization and assessment of clinical outcomes and adverse events. The studied parameters included self-reported outcomes (pain, disability and satisfaction) and complications.
Results::
46 articles fulfilling the inclusion criteria were reviewed providing results for 2026 patients with a mean follow-up of 33 months. The post-operative improvements in terms of pain and disability were significant. Subjective assessment showed an overall patient satisfaction of 83.4%. Radiographic ASD occurred in 0 to 34% of patients. Device breakage occurred in 0 to 30%, and device loosening in 0 to 72% of patients. The global amount of revision surgeries reached 9.4% mainly for breakage, ASD or persistent pain, not always associated with screw-loosening.
Conclusions::
Dynamic stabilization appears as safe and effective but benefits might partly come from decompressive gestures. Reported clinical outcomes seems to be comparable to outcomes published for fusion and no clear evidence of protection of the adjacent segments emerge from this mid-term review. Technical failures are design-related but also linked with patient specificities. Relationships between sagittal balance and surgery outcomes are still rarely reported. Dynamic stabilization might display advantages in selected indications, such as moderate degeneration and beginning instability associated with clinical symptoms, but further clinical studies are needed.
OBJECTIVE: Adult isthmic spondylolisthesis can be treated with direct repair of the defect, decompression (alone or with posterolateral fusion), circumferential fusion, and reduction with posterior fixation. The aim of this work is to assess the mid-term results of decompression and in situ fusion among patients undergoing surgical treatment with the same surgeon. METHOD: Inclusion criteria: 1) L5-S1 Isthmic spondylolisthesis. 2) Surgery performed after skeletal maturity. 3) L5 laminectomy and arthrectomy with posterolateral instrumented fusion without reduction. 4) Follow-up greater than 3 years. 5) No pseudoarthrosis at follow-up. 6) Functional and radiological assessment by independent observers; literature review and data comparison; statistical analysis with t-test, chi-squared and ANOVA. RESULTS: 16 patients were evaluated (12 ♀/4 ♂). Mean age: 40.6 years (17-66); mean follow-up: 10.3 years (3.3-18). Average slip: 42.9%. Nine patients had radicular pain, 3 back pain and 4 both. Mean preoperative SRS pain score: 1.38 with no differences between low and high degree (p=0.887). Fifteen of 16 patients had improvement of symptoms (mean final score: 4.44). Thirteen of 16 patients returned to previous activity (81%). There were 2 infections, but no neurologic complications. The spino-pelvic parameters at the end of the follow-up showed no statistical differences compared with the values found in literature. The comparison between low and high degree listhesis in our series showed no significant difference in these parameters or in the follow-up period, fused levels, symptoms or return to work. CONCLUSION: The posterolateral decompression and instrumented fusion in situ allow 80% of good results in lumbosacral isthmic spondylolisthesis in adults regardless of the degree of slip.
Standing posture is made possible by hip extension and lumbar lordosis. Lumbar lordosis is correlated with pelvic parameters, such as the declivity angle of the upper surface of the sacrum and the incidence angle, which determine the sagittal morphotype. Incidence angle, which is different for each individual, is known to be very important for up-right posture, but its course during life has not yet been established. Incidence angle was measured on radiographs of 30 fetuses, 30 children and 30 adults, and results were analysed using the correlation coefficient r and Student's t test. A statistically significant correlation between age and incidence angle was observed. Incidence angle considerably increases during the first months, continues to increase during early years, and stabilizes around the age of 10 years. Incidence is a mark of bipedism, and its role in sagittal balance is essential.
A prospective analysis of the sagittal profile of 100 healthy young adult volunteers was carried out in order to evaluate the relationship between the shape of the pelvis and lumbar lordosis and to create a databank of the morphologic and positional parameters of the pelvis and spine in a normal healthy population. Inclusion criteria were as follows: no previous spinal surgery, no low back pain, no lower limb length inequality, no scoliotic deviation. For each subject, a 30 x 90-cm sagittal radiograph including spine, pelvis and proximal femurs in standing position on a force plate was performed. The global axis of gravity was determined with the force plate. Each radiograph was digitized using dedicated software. The spinal parameters registered were values for thoracic kyphosis and lumbar lordosis. The pelvic angles measured were: pelvic incidence, sacral slope and pelvic tilt. The global axis of gravity was on average 9 mm anterior of the center of the femoral heads. The anatomic parameter of pelvic incidence angle varied from 33 degrees to 85 degrees (mean: 51.7 degrees, SD: 11 degrees). The average lumbar lordosis was 46.5 degrees. The average thoracic kyphosis was 47 degrees. We found a statistical correlation between incidence angle and lumbar lordosis (r=0.69, P<0.001) and between sacral slope angle and lumbar lordosis (r=0.75, P<0.001). Spine and pelvis balance around the hip axis in order to position the gravity line over the femoral heads. We propose a scheme of sagittal balance of the standing human body.
The anatomic pelvic parameter "incidence" - the angle between the line perpendicular to the middle of the sacral plate and the line joining the middle of the sacral plate to the center of the bicoxo-femoral axis - has been shown to be strongly correlated with the sacral slope and lumbar lordosis, and ensures the individual an economical standing position. It is important for determining the sagittal curve of the spine. The angle of incidence has also been shown to depend partly on the sagittal anatomy of sacrum, which is established in childhood while learning to stand and walk. The purpose of this study was (1) to define the relationship between the sacrum and the angle of incidence, and (2) to compare these parameters in three populations: young adults, infants before walking, and patients with spondylolisthesis. Forty-four normal young adults, 32 infants not yet walking and 39 patients with spondylolisthesis due to isthmic spondylolysis underwent a sagittal full-spine radiography. A graphic table and the software for bidimensional study of the sacrum developed by J. Hecquet were used to determine various anatomic and positional parameters. Comparison tests of means, and multiple and partial correlation tests were used. A study of the reliability of the measurements using factorial plan methods was performed. The sagittal anatomic parameters of the sacrum were found to have a close relationship with the pelvic parameter of incidence angle, and therefore with the sagittal balance of the spine. The anatomy of the sacrum in spondylolisthesis patients is particular in that some features are much like those of young infants, but it is more curved and the incidence angle is significantly larger. There is a close relationship between angle of incidence and the slip of spondylolisthesis. All the parameters of young infants are significantly smaller than those of adults. It can be concluded that the sagittal anatomy of the sacrum plays a key role in spinal sagittal balance. The sacral bone is an integral a part of the pelvis and constitutes the undistorted part of the spinal curves. Organization of sagittal curves during growth can be followed up by looking at the sacrum. The sacrum in the spondylolisthesis group differs from the normal, and the greater angle of incidence and sacral slope in this group could predispose to vertebral slip.
Purpose. The development of isthmic spondylolisthesis is influenced by forces across the lumbosacral region of the spine, Pelvic incidence is a radiographic parameter that has been shown to be an independent parameter that influences both sagittal spinal balance and pelvic orientation. Our hypothesis then is that there is a positive correlation between pelvic incidence and spondylolisthesis. Study Design, A radiographic analysis of cases with spondylolisthesis. Objectives. To try to assess the correlation between pelvic incidence in both low-grade and high-grade spondylolisthesis in both a pediatric and an adult population. Summary of Background Data. The concept of pelvic incidence has been introduced into the literature. Its exact association with spondylolisthesis has not yet been clarified. Methods. Forty patients with spondylolisthesis were identified and divided into two groups: low-grade (Meyerding I-II) and high-grade (Meyerding III and higher). Radiographic parameters measured included lumbar sagittal alignment (T12-S1), sacral inclination, slip angle, and pelvic incidence. The spondylolisthesis was classified according to the Meyerding-Newman classifications and the slip angle. Radiographic measurements were also done in two control groups; there were 20 pediatric and 20 adult controls (mean age 11.8 years and 60,0 years, respectively). Unpaired t test analysis and Pearson correlation analysis were then done. Results. Mean pelvic incidence was 47.4degrees in the pediatric control group, 57degrees in the adult control group, 68.5degrees in the low-grade isthmic spondylolisthesis group, and 79.0degrees in the high-grade isthmic spondylolisthesis group. Pelvic incidence was found to be significantly higher in the high- and low-grade spondylolisthesis groups compared with both control groups (P = 0.0001). Pelvic incidence was significantly higher in the high-grade isthmic spondylolisthesis group than in the low-grade isthmic spondylolisthesis group (P = 0.007). A significant correlation existed between pelvic incidence and Meyerding-Newman scores (P = 0.03). Conclusions, Pelvic incidence was significantly higher in patients with low- and high-grade isthmic spondylolisthesis as compared with controls and had significant correlation with the Meyerding-Newman grades (P = 0.03).
Study Design. An anatomic and radiographic study of archeological skeletal remains from two genetically and geographically distinct groups with high occurrence rates of spondylolytic spondylolisthesis was done. Specimens were Aleut (27% known occurrence rate, n = 48) and Arikara Plains Indians (9% occurrence, n = 250+ of 1,062). Objective. To evaluate three radiographic parameters highly correlated with spondylolisthesis (pelvic incidence [PI], sacral table angle [STA], and lumbar index [LI]) in genetically homogeneous populations to determine which may be etiologic or most predictive for lysis. Summary of Background Data. LI has been known to vary with the percentage of slip in lytic spondylolisthesis. Recent clinical studies have shown that PI is also significantly higher in high-grade slips, and a possible etiologic effect has been ascribed to this association. STA has also been shown to vary between normals, those with only lysis, and those with lysis and slip. The etiologic significance of STA is unknown. Methods. Radiographic and direct morphologic measurement of PI, LI, and STA was done on L5 and reassembled sacra and ilia. Statistical analysis of these three parameters among all groups was done. Results. 1) There is a genetically determined difference in the upper sacral tilt (STA) that may be etiologic. 2) Genetically homogeneous groups with a lower STA in normal specimens have an increased occurrence rate of spondylolysis. 3) When there has been pars lysis, changes in the STA occur as well as deformity more caudal in the sacrum. 4) These changes are likely related to remodeling with epiphyseal growth related to changed axial stresses secondary to pars lysis. 5) PI is not a primary etiologic factor in the process. Conclusions. The STA in the normal population for each genetic group varies and relates significantly to the occurrence rate and is thus probably etiologic. STA is more highly associated with the occurrence of pars defect than is PI. Upper sacral deformities appear due to the growth plate response to the changed pressure gradients across the epiphyseal plate rather than interosseous remodeling of the ilium and acetabular area. Thus, changes in PI would be secondary.
Lumbosacral spondylolisthesis was provoked experimentally in growing rabbits by means of a bilateral facet joint resection at the L7-S1 segment. The effects of additional immobilization of the L6-L7 segment with bone cement and of severing the lumbosacral disc on the development of the olisthesis were tested. A mean ventral slip of 21% was seen after the facet joint resection. The slip resembled the spondylolisthesis seen in humans in wedging of the olisthetic vertebra, sacral rounding, and increased sagittal rotation. Combining the facet joint resection with immobilization of the L6-L7 segment resulted in a mean slip of 15%. Morphologic features of the slip were like those seen after a plain facet joint resection. A different result was seen after facet joint resection was combined with severing of the lumbosacral disc. The mean slip was only 6%, and sacral rounding was a prominent feature. This experiment shows that an upright posture of the spine is not a prerequisite for the development of spondylolisthesis. A bilateral facet joint resection in a growing rabbit results in a human like spondylolisthesis. This model may help further experimental studies concerning the changes in the olisthetic disc.
Study Design and Objectives. Pelvic morphology and lumbopelvic lordosis were measured on standing radiographs of 75 patients with greater than 10% L5-S1 spondylolytic spondylolisthesis. The findings were compared with those of 75 volunteers to determine significant differences between the two groups.
Summary of Background Data. Etiology of isthmic (lytic) spondylolisthesis remains uncertain. Causation appears to be multifactorial. The relationship between pelvic morphology and spondylolisthesis deserves additional study.
Methods. Both groups had a standing lateral radiograph of the thoracolumbar spine and pelvis taken that included both hips. Three radiographic angles for pelvic morphology (pelvisacral, pelvic incidence, and pelvic lordosis) were measured by two observers. Each offered similar reliability. Measurement of the pelvic lordosis angle by the pelvic radius technique required fewer steps. It also allowed calculation of the combined angles comprising both the pelvic morphology component for lordosis (the constant pelvic lordosis angle) and the lordosis in the lumbar spine (the variable lumbar lordosis from T12-S1) that should complement the fixed pelvic lordosis (the complementary lumbopelvic lordosis). Mean values and statistical correlations were then computed for each group and compared.
Results. The mean slippage for patients was 30% (range, 11–85%), with 34 patients (45%) having Grade I slips, 32 (43%) having Grade II slips, and nine (12%) having Grade III and IV slips. The mean measurements between patients and volunteers were significantly different (P < 0.01) for lumbar lordosis, pelvic lordosis, and lumbopelvic lordosis. Subgroups of patients with increasingly larger slips (Grade I–III) had significantly smaller mean angles for pelvic lordosis.
Conclusions. The pelvic and lumbopelvic parameters studied were different in patients compared with controls. The contribution of the pelvis to lordosis was significantly smaller in the subgroups of patients with increasingly larger grades of spondylolisthesis. Pelvic morphology may play a role in the development of spondylolisthesis. Measurement of the combined lumbar and pelvic (lumbopelvic) lordosis on standing radiographs is important.
This study was designed to investigate the relationship between postural deformities--including both the spine and lower extremities--and clinical symptoms in spinal osteoporotics. Lateral roentgenographic films of 100 osteoporotic patients taken in a standing position were analyzed. Thoracic kyphosis, a primary deformity of the osteoporotic spine, appeared compensated by the lumbar spine, sacroiliac joint, hip joint, and knee joint, respectively. Low-back pain was highly associated with decreased lumbar lordosis and increased sacropelvic angle, suggesting that the sacroiliac joint was one of the causes of low-back pain.
On theoretic grounds it can be assumed that aberrations of posture may play a role in the generation of low-back pain by creating concentrations of stress. However, this assumption remains speculative because of the absence of criteria for normal posture. This study considers some of these criteria, especially as they are related to the lumbar spine and pelvis. The relations between the angle of declivity of the sacrum and radius and inclination of the lordotic curvature of the lumbar spine show good correlation. Mean values of postural parameters in the group of spondylolysis patients differ significantly from those in the group of healthy volunteers.
A global and segmental study on standing lateral radiographs of 100 volunteers and 100 patients who had low back pain was undertaken to further define sagittal plane alignment and balance. The volunteer control group and the patient group were matched for age, sex, and size.
Measurements and determinations made on the standing radiographs included the following: segmental and total lordosis L1-S1 (Cobb method); thoracic kyphosis; thoracic apex; plumbline dropped from the center of C7; and sacral inclination measured between the plumbline and a line drawn along the back of the proximal sacrum.
Segmental lordoses were significantly different between each motion segment in both groups. Approximately two-thirds of total lordosis occurred at the bottom two discs, i.e., L4-5 and L5-S1. Total lordosis was significantly less in the patients and was not age- or sex-related in either group. Patients tended to stand with less distal segmental lordosis, but more proximal lumbar lordosis, a more vertical sacrum and, therefore, more hip extension. This may be related to compensation as C7 sagittal plumb lines were comparable in both groups. Both groups had similar thoracic kyphosis. A much higher percentage of smokers was found in the low back pain patient population studied. Because of the significant amount of angulation in the lower lumbar spine, measurement of lordosis should include the L5-S1 motion segment and be done standing to better assess balance. Sacral inclination is a determinate of both standing pelvic rotation and hip extension. It is strongly correlated with segmental and total lordosis in both volunteers and patients.
Definitions of sagittal balance are provided as well as additional sagittal plane data by which to compare corrections and fusions for different spinal disorders.
Lumbosacral spondylolisthesis was provoked experimentally in growing rabbits by means of a bilateral facet joint resection at the L7-S1 segment. The effects of additional immobilization of the L6-L7 segment with bone cement and of severing the lumbosacral disc on the development of the olisthesis were tested. A mean ventral slip of 21% was seen after the facet joint resection. The slip resembled the spondylolisthesis seen in humans in wedging of the olisthetic vertebra, sacral rounding, and increased sagittal rotation. Combining the facet joint resection with immobilization of the L6-L7 segment resulted in a mean slip of 15%. Morphologic features of the slip were like those seen after a plain facet joint resection. A different result was seen after facet joint resection was combined with severing of the lumbosacral disc. The mean slip was only 6%, and sacral rounding was a prominent feature. This experiment shows that an upright posture of the spine is not a prerequisite for the development of spondylolisthesis. A bilateral facet joint resection in a growing rabbit results in a human like spondylolisthesis. This model may help further experimental studies concerning the changes in the olisthetic disc.
This paper proposes an anatomical parameter, the pelvic incidence, as the key factor for managing the spinal balance. Pelvic and spinal sagittal parameters were investigated for normal and scoliotic adult subjects. The relation between pelvic orientation, and spinal sagittal balance was examined by statistical analysis. A close relationship was observed, for both normal and scoliotic subjects, between the anatomical parameter of pelvic incidence and the sacral slope, which strongly determines lumbar lordosis. Taking into account the Cobb angle and the apical vertebral rotation confers a three-dimensional aspect to this chain of relations between pelvis and spine. A predictive equation of lordosis is postulated. The pelvic incidence appears to be the main axis of the sagittal balance of the spine. It controls spinal curves in accordance with the adaptability of the other parameters.
Sagittal alignments, including lumbar lordosis and spinopelvic balance (measured from C7, S1, and hip axis reference points for the relative positions of the spine and sacropelvis over the hips), were studied on standing 36-in. lateral radiographs of adult volunteers (control subjects) and patients who had specific spinal disorders.
To determine the most reliable methods for measuring lumbopelvic lordosis and to define significant spinopelvic compensations for sagittal balance.
Measurements for standing sagittal balance, obtained using a C7 plumb line, and segmental angulations of the spinal vertebrae, including lordosis to the sacrum, have been reported. Absolute values, even for normative data, have had wide variation and limited clinical usefulness. Correlations of sagittal balance with the reported spinopelvic angulations (spinal vertebral and sacropelvic angulations) have not been well defined. In addition, determinates of balance (spinal and pelvic) have not been studied for reliability, and compensatory mechanisms for maintenance of balance have not been carefully evaluated. Better recognition of the correlations and more reliable methods to measure lordosis and balance and the spinopelvic compensations for its maintenance may be beneficial in treating patients who have spinal disorders.
Measurements on standing 36-in. lateral radiographs were made for sagittal alignments in adult volunteers (n = 50) and in adult patients who had symptomatic degenerative lumbar disc disease (n = 50), low grade L5-S1 isthmic (lytic) spondylolisthesis (n = 30), and idiopathic or degenerative scoliosis (n = 30). All participants exhibited clinical compensation for balance. Data were analyzed for significant correlations within each group to determine compensatory correlations of spinopelvic balance with the other sagittal alignments. Intraobserver and interobserver reliability for the parameters evaluated were calculated. This included two methods for determining lordosis (S1 end-plate and pelvic radius techniques).
Plumb line measurements for balance from the S1 and hip axis reference points, as defined, were similar in all four groups. However, the groups appeared to adjust for balance by using common and distinctive spinopelvic compensations that resulted in significantly and characteristically different angular alignments among the four groups. Lordosis and balance measurements were closely correlated, and the correlation was characterized by pelvic rotation and translation around the hip axis. The subjects with less lordosis typically stood with the C7 plumb line anterior to and at a longer distance from the sacral reference point. This was primarily because of posterior sacropelvic translation around the hip axis and not because the sagittal plumb line initially moved anteriorly away from the sacrum. This was true in all four groups and gave the appearance that the sacropelvis was less well balanced over the hips in the subjects with less lordosis. Even small differences in lordosis appeared to be associated with considerable adjustments in the other spinopelvic alignments. Therefore, it was important to determine that lordosis was lumbopelvic more reliably measured by the pelvic radius technique.
Lower lumbar lordosis, by the pelvic radius technique, and compensatory sacropelvic translation around a hip axis, in addition to measurements from this axis to the C7 plumb line, were the primary determinates and most reliable radiographic assessments for sagittal balance. Understanding the common and characteristically different compensations that occur with balance in these patients who had specific spinal disorders may help to improve their care.
Twenty volunteers and 20 patients with no prior spine surgery had two standing lateral radiographs taken, on the average, 66 months apart and 2 weeks apart, respectively.
To first determine the reliability of the measurement techniques used, and then the longitudinal variation between radiographs for the sagittal spinopelvic alignments measured in two stable populations, the one manifesting no back symptoms (volunteers) and the other showing no changes in symptoms (patients). Pelvic morphology also was assessed quantitatively, and significant correlations for the measurements were studied.
There are no published studies on longitudinal variation for measurements of sagittal spinal alignments in asymptomatic control subjects or untreated patients with stable back problems. It may be helpful to know not only how much variation in alignments can be expected between radiographs of the same individual, but also which measurements and measurement techniques offer the greatest clinical reliability and application.
Each patient in this study reported mechanical type low back pain that was constant in location and character as well as clinically consistent with symptomatic degenerative lumbar disc disease. Each patient and volunteer had 36-inch-long lateral radiographs taken of the entire thoracic and lumbar spine, which included the pelvis. After intervening periods of 1 to 4 weeks (patients) and 5 to 6 years (volunteers), a second radiograph was taken for comparison. Two observers made 24 different measurements on the radiographs including determinations for lumbopelvic lordosis, pelvic balance, and pelvic morphology using the pelvic radius technique. Reliabilities, longitudinal variations, and correlations for the measurements were compared.
The most reliable measurements were for pelvic morphology, pelvic balance, and regional lumbopelvic lordosis by the pelvic radius technique. Pelvic morphology was the most constant measurement between individual radiographs. Pelvic morphology and total lumbosacral lordosis were dependent measurements that were complementary in determining total lumbopelvic lordosis. Lumbopelvic lordosis and pelvic balance also had strong correlation, whereas lumbosacral lordosis and pelvic balance were independent measurements.
The pelvic radius technique is recommended for evaluating lordosis to the pelvis because this approach provided not only good measurement reliability on standing radiographs for lumbopelvic lordosis, but also determination of pelvic balance over the hips and the option to assess pelvic morphology quantitatively. Lumbopelvic lordosis and pelvic balance were strongly correlative. This finding, along with higher reliability and lower longitudinal variation on repeated radiographs, indicated greater clinical application for these specific measurements.
Radiographs of 75 healthy volunteers were measured to decide parameters and ranges for "congruent" sagittal spinopelvic alignments using the pelvic radius technique. A subset of 30 of the volunteers subsequently had a second radiograph to assess for changes in the repeated measurements.
Measurement of spinal alignment is important. Radiographic parameters for "congruent" spinopelvic balance over the hips and changes in sagittal spinal alignments over time have not been defined. Measurement techniques for spinal alignments and to quantitate pelvic morphology need to be standardized.
The 75 volunteers (44 men/31 women, mean age 39 years, range, 20 to 63 years) had 36-inch standing lateral radiographs of the thoracolumbar spine and pelvis taken that included both hips. Thirty volunteers (19 men/11 women) had a second radiograph taken 5 to 6 years later. Radiographic measurements were made using the pelvic radius technique. This required locating a midpoint between the approximate centers of both femoral heads to establish a pelvic hip axis. A line between the hip axis and the posterior superior corner of S1 for the pelvic radius was drawn and measured for length. Angles were measured from the pelvic radius to tangents along the vertebral endplates on the 105 films with an electronic digital readout device. These angles included PR-S1 for pelvic morphology and PR-T12 for total lumbopelvic lordosis. A pelvic angle was measured from a vertical line through the hip axis to the pelvic radius. This angle gave the sagittal alignment for the pelvis over the hips. Longitudinal measurements between radiographs were compared for minimum and maximum change. Significant statistical correlations for the measurements were carefully studied to determine potentially important clinical relationships. In addition, thoracic kyphosis/lumbar lordosis ratios were assessed.
The most constant measurement with the least change on the repeated radiographs was that for pelvic morphology (PR-S1 angle) followed by length of the pelvic radius, pelvic alignment over the hips (pelvic angle), and total lumbopelvic (PR-T12) and lumbosacral (T12-S1) lordosis. Other longitudinal measurements, including those for thoracic kyphosis and spinal balance by a plumbline, showed greater change. Measurements for pelvic morphology by the pelvic radius technique were correlative with standing total lumbosacral lordosis, regional lumbopelvic lordosis, pelvic alignment, pelvic radius length, and gender (P< or = 0.006 for each). The correlations between total and regional lumbopelvic lordosis and pelvic alignment measurements were even higher(P<0.0001). Of possible clinical importance was the finding that standard measurements for lordosis were dependent on individual pelvic morphology quantitated by the pelvic radius technique.
In all of the sagittally balanced subjects studied, "congruent" spinopelvic alignment on all 105 standing lateral radiographs could be defined by four parameters using the pelvic radius technique: total lumbopelvic lordosis (PR-T12), incorporating complementary angles for lumbosacral lordosis (T12-S1), and pelvic morphology (PR-S1 angle) that summarily were always between -69 degrees to -116 degrees (+/-3 degrees ); centered pelvic alignment over the hips, as determined by the pelvic angle, that was always between -3 degrees to -32 degrees (+/-2 degrees ); compensated spinal balance, with a sagittal plumbline from the center of the T4 body always posterior to the hip axis as well as the center of the L4 vertebral body; and a concordant T4-T12 kyphosis/PR-T12 lordosis ratio that was always negative and between 0.15 to 0.75. [Key words: congruent alignment, pelvic radius technique, pelvic morphology, lumbopelvic lordosis, lumbosacral lordosis]
A radiographic and morphologic study was conducted to investigate low-grade spondylolisthesis in cases with preexisting isthmic spondylolysis of L5.
To distinguish radiographically between vertebral slips before and after skeletal maturity as determined by deformities of the sacral endplate.
Very few reports have shown that spondylolisthesis with preexisting isthmic defects of L5 develops frequently in adulthood. The prognostic factors of the vertebral slip have remained unclear. It is hard to determine the onset time of low-grade spondylolisthesis.
This study examined plain radiographs of 367 adult patients with pars defects of L5 (213 without slippage and 154 with Grade 1 or 2 spondylolisthesis) and 310 control subjects, ages 20 to 59 years at the first visit. The following parameters were measured and analyzed for each age decade: the sacral table index (anteroposterior width of the sacral endplate expressed as a percentage of the anteroposterior diameter of the upper L5 endplate), the sacral table angle (formed by the sacral endplate with the posterior wall of S1), the relative thickness of the L5 transverse process, and the iliac crest height.
The prevalence of patients with slippage who met deformity criteria (sacral table index > 102% [the mean plus 2 standard deviations of the controls] and sacral table angle </=97 degrees [the mean of the controls]) remained almost one fourth during all decades. On the contrary, the prevalence of patients with slippage who met normal-shape criteria (sacral table index </=102% and sacral table angle >/=89 degrees [mean minus 2 standard deviations of the controls]) was 0% in the third decade, but increased remarkably in the fifth and sixth decades. Of the 213 patients without slippage, 8 patients in whom new slippage developed during long-term follow-up evaluation all had a normally-shaped sacral table. The prevalence of patients without slippage decreased gradually with age, and elderly patients had relatively broader transverse processes and a higher iliac crest line.
The authors considered that the slips with and those without deformities of the sacral table had developed in adolescence and adulthood, respectively. Using new radiographic parameters that indicate widening and tilting of the sacral table, low-grade isthmic spondylolis thesis can be categorized into "adolescent and adult vertebral slips."
Pelvic morphology and lumbopelvic lordosis were measured on standing radiographs of 75 patients with greater than 10% L5-S1 spondylolytic spondylolisthesis. The findings were compared with those of 75 volunteers to determine significant differences between the two groups.
Etiology of isthmic (lytic) spondylolisthesis remains uncertain. Causation appears to be multifactorial. The relationship between pelvic morphology and spondylolisthesis deserves additional study.
Both groups had a standing lateral radiograph of the thoracolumbar spine and pelvis taken that included both hips. Three radiographic angles for pelvic morphology (pelvisacral, pelvic incidence, and pelvic lordosis) were measured by two observers. Each offered similar reliability. Measurement of the pelvic lordosis angle by the pelvic radius technique required fewer steps. It also allowed calculation of the combined angles comprising both the pelvic morphology component for lordosis (the constant pelvic lordosis angle) and the lordosis in the lumbar spine (the variable lumbar lordosis from T12-S1) that should complement the fixed pelvic lordosis (the complementary lumbopelvic lordosis). Mean values and statistical correlations were then computed for each group and compared.
The mean slippage for patients was 30% (range, 11-85%), with 34 patients (45%) having Grade I slips, 32 (43%) having Grade II slips, and nine (12%) having Grade III and IV slips. The mean measurements between patients and volunteers were significantly different (P < 0.01) for lumbar lordosis, pelvic lordosis, and lumbopelvic lordosis. Subgroups of patients with increasingly larger slips (Grade I-III) had significantly smaller mean angles for pelvic lordosis.
The pelvic and lumbopelvic parameters studied were different in patients compared with controls. The contribution of the pelvis to lordosis was significantly smaller in the subgroups of patients with increasingly larger grades of spondylolisthesis. Pelvic morphology may play a role in the development of spondylolisthesis. Measurement of the combined lumbar and pelvic (lumbopelvic) lordosis on standing radiographs is important.
The development of isthmic spondylolisthesis is influenced by forces across the lumbosacral region of the spine. Pelvic incidence is a radiographic parameter that has been shown to be an independent parameter that influences both sagittal spinal balance and pelvic orientation. Our hypothesis then is that there is a positive correlation between pelvic incidence and spondylolisthesis.
A radiographic analysis of cases with spondylolisthesis.
To try to assess the correlation between pelvic incidence in both low-grade and high-grade spondylolisthesis in both a pediatric and an adult population.
The concept of pelvic incidence has been introduced into the literature. Its exact association with spondylolisthesis has not yet been clarified.
Forty patients with spondylolisthesis were identified and divided into two groups: low-grade (Meyerding I-II) and high-grade (Meyerding III and higher). Radiographic parameters measured included lumbar sagittal alignment (T12-S1), sacral inclination, slip angle, and pelvic incidence. The spondylolisthesis was classified according to the Meyerding-Newman classifications and the slip angle. Radiographic measurements were also done in two control groups; there were 20 pediatric and 20 adult controls (mean age 11.8 years and 60.0 years, respectively). Unpaired t test analysis and Pearson correlation analysis were then done.
Mean pelvic incidence was 47.4 degrees in the pediatric control group, 57 degrees in the adult control group, 68.5 degrees in the low-grade isthmic spondylolisthesis group, and 79.0 degrees in the high-grade isthmic spondylolisthesis group. Pelvic incidence was found to be significantly higher in the high- and low-grade spondylolisthesis groups compared with both control groups (P = 0.0001). Pelvic incidence was significantly higher in the high-grade isthmic spondylolisthesis group than in the low-grade isthmic spondylolisthesis group (P = 0.007). A significant correlation existed between pelvic incidence and Meyerding-Newman scores (P = 0.03).
Pelvic incidence was significantly higher in patients with low- and high-grade isthmic spondylolisthesis as compared with controls and had significant correlation with the Meyerding-Newman grades (P = 0.03).
Retrospective analysis of pelvic incidence and other radiographic parameters as a predictor of progression of isthmic spondylolisthesis.
To evaluate the predictive value of various radiographic parameters, including pelvic incidence, in determining the risk for progression of lumbosacral isthmic spondylolisthesis. SUMMARY OF BACKGROUND DATA Although pelvic incidence has recently been shown to be positively correlated to the severity of spondylolisthesis, it has not been confirmed as a predictor of spondylolisthetic progression.
Thirty-six patients who have undergone primary posterior lumbosacral fusion for isthmic spondylolisthesis at our institution from 1977 to 2001 were retrospectively analyzed. There were 24 females and 12 males with a mean age of 21.3 +/- 2.0 years (range, 12 to 53 y). Twenty-two patients had high-grade (Meyerding class III, IV, V) and 14 patients had low-grade (Meyerding class I, II) spondylolisthesis, respectively. Factors evaluated included age, gender, neurologic deficits, reason for surgery, and documented evidence of progression. Slip percentage, high-grade or low-grade slip, slip angle, sacral inclination, sacral rounding, trapezoidal L5 vertebra, and pelvic incidence were measured from immediate preoperative standing lateral radiographs. These factors were statistically analyzed for risk of progression. Continuous variables were analyzed using one-way analysis of variance. Nominal variables were analyzed using chi2 test.
Pelvic incidence (P = 0.66) was not predictive of spondylolisthetic progression. Of the other radiographic measurements, slip percentage (P < 0.001), slip angle (P = 0.016), and high-grade spondylolisthesis (P < 0.0001) were highly predictive of progression. Interestingly, sacral inclination (P = 0.33) was not predictive of progression.
Pelvic incidence cannot adequately predict the probability of spondylolisthetic progression. Analysis of the other clinical and radiographic parameters revealed that slip percentage and high-grade spondylolisthesis remain the most positive predictors of progression.
Background context:
Maintenance of normal lumbar lordosis is important in the treatment of spinal disorders. Many attempts have been made to quantify normal sagittal spinal alignment and lordosis using a C7 plumb line and segmental angulations of the spinal vertebrae. Little attention has been given to pelvic compensation as it correlates to lumbar lordosis and overall sagittal spinal alignment. Better methods of measuring lordosis, which correlate with sagittal spinal balance and pelvic compensation, are needed in treating patients with spinal disorders.
Purpose:
To determine the correlation between lumbopelvic lordosis, pelvic rotation and sagittal spinal balance and standardize a method for measuring lumbopelvic lordosis, sacral translation, and sagittal spinal alignment.
Study design:
Sagittal alignments using the C7 plumb line, Cobb angles, sacral plumb line and the pelvic radius (PR) technique were used to measure standing 36-inch lateral radiographs of patients with various spinal disorders.
Patient sample:
A review of the records identified 62 patients with various spinal pathologies presenting to the (RGW) spine clinic that had standing lateral spine radiographs. Only radiographs that allowed positive identification of the C7 vertebral body, the entire thoracolumbar spine, the sacrum and both femoral heads were studied. These criteria allowed inclusion of 28 subjects in this study. The final population had 12 women and 16 men with an average age of 52 years (SD, 16.6 years; range, 20 to 84 years).
Outcome measures:
No outcomes measures were used in this study.
Methods:
Measurements for sagittal spinal balance and lumbopelvic lordosis were made on 36-inch standing lateral radiographs of adult patients. Measurements included the C7 plumb line, segmental angulations of spinal vertebrae (Cobb angles), sacral translation and the PR technique for lumbopelvic lordosis. Data were analyzed for significant correlation between lumbopelvic lordosis, sagittal spinal balance, sacral translation and total segmental lumbar lordosis using the Cobb method.
Results:
Our population averaged 50 degrees of total segmental lumbar lordosis from L1 to S1 (SD, 14.3; maximum, 89.5; minimum, 17.9). Nearly 75% of total segmental lumbar lordosis measured from L1 to S1 can be accounted for through the L4 to S1 superior end plates and 47% through L5 to S1 superior end plates in our population. Total segmental lumbar lordosis correlated with total thoracic kyphosis (r=0.45, p=.008). Total segmental lumbar lordosis measured by the Cobb method significantly correlated with sagittal spinal balance (r=-0.35, p=.022) and sacral translation (r=0.41, p=.016). Measurements for lumbopelvic lordosis significantly correlated with sagittal spinal balance (r=-0.33, p=.042), sacral translation (r=-0.70, p=.00002) and total segmental lumbar lordosis (r=0.82, p<.000001). Measurements for sacral translation and sagittal spinal balance also correlated significantly (r=0.35, p=.034).
Conclusions:
Sacral translation, the C7 plumb line and lumbopelvic lordosis are useful measures for sagittal spinal balance. Lumbopelvic lordosis and sacral translation can be correlated to the sagittal spinal balance. Understanding these measurements and the range of lumbopelvic compensation can be extremely helpful in treating patients with spinal pathology and in avoidance of flatback deformity. Application of these measures would be especially helpful in the treatment of patients with spinal fusion, degenerative spondylosis, disc disease, fractures, and in the prevention of sagittal malalignment.
Sagital balance of the spine is a fundamental element necessary for understanding spinal disease and instituting proper treatment. The aim of this prospective work was to establish the physiological values of pelvic and spinal parameters of sagital balance of the spine and to investigate their interactions.
Pelvic and spinal parameters were measured on the standing radiographs of 250 healthy volunteers. The following parameters were measured on lateral views including the head, the spine and the pelvis: lumbar lordosis, thoracic kyphosis, sagital tilt at T9, sacral inclination, pelvic incidence, pelvic version, intervertebral angulation, and the vertebral cuneiformization from T9 to S1. These measurements were taken after digitalization of the radiographs. Two types of analysis were performed: a descriptive univariate analysis to characterize the angular parameters and multivariate analysis (correlation, principal component analysis) to detail the relative variations of these parameters.
Mean values were: maximal lumbar lordosis 61 +/- 12.7 degrees, maximal thoracic kyphosis 41.4 +/- 9.2 degrees, sacral inclination 44.2 +/- 8.5 degrees, pelvic version 13 +/- 6 degrees, pelvic incidence 55 +/- 11.2 degrees, sagital tilt at T9 10.5 +/- 3.1 degrees. There was a strong correlation between sacral inclination and pelvic incidence (r=0.86), pelvic version and pelvic incidence (r=0.66), lumbar lordosis pelvic incidence pelvic version and thoracic kyphosis (r=0.9) and finally between pelvic incidence and the following parameters: sagital tilt at T9, sacral inclination, pelvic version, lumbar lordosis, and thoracic kyphosis (r=0.98). The relations between the different parameters studied demonstrated that saggital tilt at T9, which reflects spinal balance, is determined by three independent factors. The first is a linear combination of pelvic incidence, lumbar lordosis, and sacral inclination. The second is pelvic version. The third is thoracic kyposis.
This work provided a useful tool for analyzing and understanding anteroposterior imbalance in patients with spinal disease and also a means of calculating corrections to be made with treatment, established from the linear regression equations which were elaborated.
Prospective study of the sagittal plane alignment of the spine and pelvis in the normal pediatric population.
To document the sagittal alignment of the spine and pelvis and its change during growth in the normal pediatric population.
Pelvic morphology as well as sagittal alignment of the spine and pelvis in the pediatric population are poorly defined in the literature.
Five parameters were evaluated on lateral standing radiographs of 180 normal study participants 4 to 18 years of age: thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. Statistical analysis was performed using two-tailed Student t tests and Pearson's coefficients (level of significance = 0.01).
The mean thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence values were 43.0 degrees, 48.5 degrees, 41.2 degrees, 7.2 degrees and 48.4 degrees, respectively. There was no significant difference between males and females. Thoracic kyphosis, lumbar lordosis, pelvic tilt, and pelvic incidence were found to be weakly correlated with age, while sacral slope remained stable with growth.
Pelvic morphology, as measured by the pelvic incidence angle, tends to increase during childhood and adolescence before stabilizing into adulthood, most likely to maintain an adequate sagittal balance in view of the physiologic and morphologic changes occurring during growth. Pelvic tilt and lumbar lordosis, two position-dependent parameters, also react by increasing with age, most likely to avoid inadequate anterior displacement of the body center of gravity. Sacral slope is achieved with the standing posture and is not further significantly influenced by age. These results are important to establish baseline values for these measurements in the pediatric population, in view of the reported association between pelvic morphology and the development of various spinal disorders such as spondylolisthesis and scoliosis.
A prospective radiographic study of 160 volunteers without symptoms of spinal disease was conducted.
The objective of this study was to describe, quantify, and classify common variations in the sagittal alignment of the spine, sacrum, and pelvis.
Previous publications have documented the high degree of variability in the sagittal alignment of the spine. Other studies have suggested that specific changes in alignment and the characteristics of the lumbar lordosis are responsible for degenerative changes and symptomatic back pain.
In the course of this study, anteroposterior and lateral radiographs of 160 volunteers in a standardized standing position were taken. A custom computer application was used to analyze the alignment of the spine and pelvis on the lateral radiographs. A four-part classification scheme of sagittal morphology was used to classify each patient.
Reciprocal relationships between the orientation of the sacrum, the sacral slope, the pelvic incidence, and the characteristics of the lumbar lordosis were evident. The global lordotic curvature, lordosis tilt angle, position of the apex, and number or lordotic vertebrae were determined by the angle of the superior endplate of S1 with respect to the horizontal axis.
Understanding the patterns of variation in sagittal alignment may help to discover the association between spinal balance and the development of degenerative changes in the spine.
There is an increasing recognition of the clinical importance of the sagittal plane alignment of the spine. A prospective study of several radiographic parameters of the sagittal profile of the spine was conducted to determine the physiological values of these parameters, to calculate the variations of these parameters according to epidemiological and morphological data, and to study the relationships among all of these parameters.
Sagittal radiographs of the head, spine, and pelvis of 300 asymptomatic volunteers, made with the subject standing, were evaluated. The following parameters were measured: lumbar lordosis, thoracic kyphosis, T9 sagittal offset, sacral slope, pelvic incidence, pelvic tilt, intervertebral angulation, and vertebral wedging angle from T9 to S1. The radiographs were digitized, and all measurements were performed with use of a software program. Two different analyses, a descriptive analysis characterizing these parameters and a multivariate analysis, were performed in order to study the relationships among all of them.
The mean values (and standard deviations) were 60 degrees 10 degrees for maximum lumbar lordosis, 41 degrees +/- 8.4 degrees for sacral slope, 13 degrees +/- 6 degrees for pelvic tilt, 55 degrees +/-10.6 degrees for pelvic incidence, and 10.3 degrees +/- 3.1 degrees for T9 sagittal offset. A strong correlation was found between the sacral slope and the pelvic incidence (r = 0.8); between maximum lumbar lordosis and sacral slope (r = 0.86); between pelvic incidence and pelvic tilt (r = 0.66); between maximum lumbar lordosis and pelvic incidence, pelvic tilt, and maximum thoracic kyphosis (r = 0.9); and, finally, between pelvic incidence and T9 sagittal offset, sacral slope, pelvic tilt, maximum lumbar lordosis, and thoracic kyphosis (r = 0.98). The T9 sagittal offset, reflecting the sagittal balance of the spine, was dependent on three separate factors: a linear combination of the pelvic incidence, maximum lumbar lordosis, and sacral slope; the pelvic tilt; and the thoracic kyphosis.
This description of the physiological spinal sagittal balance should serve as a baseline in the evaluation of pathological conditions associated with abnormal angular parameter values. Before a patient with spinal sagittal imbalance is treated, the reciprocal balance between various spinal angular parameters needs to be taken into account. The correlations between angular parameters may also be useful in calculating the corrections to be obtained during treatment.
A review article.
The purpose of this article is to review pertinent radiologic measurements for the evaluation of spino-pelvic balance in developmental spondylolisthesis, based on the experience of the Spinal Deformity Study Group.
Over the past decade, pelvic morphology has been shown to significantly influence spino-pelvic balance of the human trunk in normal and pathologic conditions. This finding has important implications for the evaluation and treatment of developmental spondylolisthesis and has fostered a renewed interest in the radiologic evaluation of spino-pelvic balance in this condition.
The lateral standing radiographs of the spine and pelvis of subjects with developmental L5-S1 spondylolisthesis were analyzed with a dedicated software allowing the calculation of the following parameters: pelvic incidence, sacral slope, pelvic tilt, L5 incidence angle, lumbosacral angle, lumbar lordosis, thoracic kyphosis, and grade of spondylolisthesis. All measurements were done by the same individual and compared to those of an adult and child reference population.
The pelvic shape, best quantified by the pelvic incidence angle, determines the position of the sacral endplate. The spine reacts to this position by adapting through lumbar lordosis, the amount of lordosis increasing as the sacral slope increases in order to balance the trunk in the upright position. Pelvic incidence, sacral slope, pelvic tilt, and lumbar lordosis are found to be significantly greater in subjects with developmental spondylolisthesis, while thoracic kyphosis is significantly lower when compared to a reference population. Furthermore, the differences between the two populations increase in a direct linear fashion as the severity of the spondylolisthesis increases, suggesting that pelvic anatomy has a direct influence on the development of a spondylolisthesis. Studies also indicate that pelvic incidence is unaffected by surgical reduction and instrumentation. Pelvic tilt, sacral slope, and thoracic kyphosis are slightly affected, while grade, L5 incidence angle, lumbosacral angle, and shape of the lumbar spine are significantly improved after surgery. A postoperative improvement in L5 incidence angle and lumbosacral angle appears correlated with a better outcome while subjects with a poor outcome have a higher preoperative grade.
Spino-pelvic balance in the sagittal plane can be considered as an open linear chain linking the head to the pelvis where the shape and orientation of each successive anatomic segment are closely related and influence the adjacent segment. Pelvic morphology and spino-pelvic balance are abnormal in developmental spondylolisthesis. These abnormalities should be quantified on lateral standing radiographs of the spine and pelvis and have important implications for the evaluation and treatment of this pathologic condition.
Retrospective review.
To review the findings in the cases of spondyloptosis we have treated and to postulate on the possible cause of spondyloptosis.
Spondyloptosis (Grade V spondylolisthesis) is rare, even though spondylolisthesis is a relatively common condition. While it is known that progression to spondyloptosis occurs in patients with developmental spondylolisthesis in their childhood and/or adolescent years, the precise factors leading to progression are not known.
Between 1979 and 2002, 27 patients with spondyloptosis were treated surgically with L5 resection and reduction of L4 onto S1. During the treatment process, detailed observations of the surgical findings were made through clinical and radiologic means. Six anatomic parameters (pars interarticularis defects, spina bifida of the L5 or sacral segments, dysplasia of the L5-S1 facet joints, L5-S1 disc degeneration, trapezoidal shape of L5, and rounding of the proximal end of the sacrum) were specifically studied.
Pars interarticularis defects were present in 24 patients (88.9%), facet dysplasia in 16 patients (59.2%), spina bifida in 24 patients (88.9%), disc degeneration in 25 (92.6%), trapezoidal L5 in 20 patients (74.1%), and rounding of the proximal end of S1 in all 27 patients (100%).
Rounding of the proximal sacral endplate was the only constant abnormal anatomic feature in the patients. Damage to the proximal sacrum and sacral growth plate during late childhood and early adolescence, similar to the epiphyseal injury that produces Blount's disease, and slipped capital femoral epiphysis seem to be key factors permitting the progression of developmental spondylolisthesis to spondyloptosis.
An anatomic and radiographic study of archeological skeletal remains from two genetically and geographically distinct groups with high occurrence rates of spondylolytic spondylolisthesis was done. Specimens were Aleut (27% known occurrence rate, n = 48) and Arikara Plains Indians (9% occurrence, n = 250+ of 1,062).
To evaluate three radiographic parameters highly correlated with spondylolisthesis (pelvic incidence [PI], sacral table angle [STA], and lumbar index [LI]) in genetically homogeneous populations to determine which may be etiologic or most predictive for lysis.
LI has been known to vary with the percentage of slip in lytic spondylolisthesis. Recent clinical studies have shown that PI is also significantly higher in high-grade slips, and a possible etiologic effect has been ascribed to this association. STA has also been shown to vary between normals, those with only lysis, and those with lysis and slip. The etiologic significance of STA is unknown.
Radiographic and direct morphologic measurement of PI, LI, and STA was done on L5 and reassembled sacra and ilia. Statistical analysis of these three parameters among all groups was done.
1) There is a genetically determined difference in the upper sacral tilt (STA) that may be etiologic. 2) Genetically homogeneous groups with a lower STA in normal specimens have an increased occurrence rate of spondylolysis. 3) When there has been pars lysis, changes in the STA occur as well as deformity more caudal in the sacrum. 4) These changes are likely related to remodeling with epiphyseal growth related to changed axial stresses secondary to pars lysis. 5) PI is not a primary etiologic factor in the process.
The STA in the normal population for each genetic group varies and relates significantly to the occurrence rate and is thus probably etiologic. STA is more highly associated with the occurrence of pars defect than is PI. Upper sacral deformities appear due to the growth plate response to the changed pressure gradients across the epiphyseal plate rather than interosseous remodeling of the ilium and acetabular area. Thus, changes in PI would be secondary.
Predictive value of pelvic incidence in progression of spondylolisthesis Radiographic classification of L5 isthmic spondylolisthesis as adolescent or adult vertebral slip
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Pelvic lordosis and alignment in spondylolisthesis The importance of spino-pelvic balance in L5-s1 developmental spondylolisthesis: a review of pertinent radiologic measurements
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The importance of spino-pelvic balance in L5-s1 developmental spondylolisthesis: a review of pertinent radiologic measurements
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Labelle H, Roussouly P, Berthonnaud
E, Dimnet J, O'Brien M (2005) The
importance of spino-pelvic balance in
L5-s1 developmental spondylolisthesis:
a review of pertinent radiologic measurements. Spine 30:S27–S34