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Classification of patella instability and maltracking. The grading is based on the main pathology, despite instability and maltracking is caused by multiple pathologies in most cases. If there are competing and comparable pathologies, the higher grading is used
Source publication
To date there is no classification of patellar dislocations considering clinical and radiological pathologies. As a result many studies mingle the dislocation's underlying pathologies, so that there are no consistent therapy recommendations. It is this article's objective to introduce a patellar dislocation classification based on the current liter...
Similar publications
Congenital dislocation of the patella is a rare disorder present at birth which manifests as a permanent and irreducible patella fixed on the lateral aspect of the femoral condyle. Congenital dislocation of the patella is frequently found in syndromic patients with a flexion contracture at the knee, genu valgum, foot deformity and external tibial t...
Purpose of Review
Obligatory dislocation of the patella (also known as habitual dislocation) is a rare subset of patellofemoral instability in which the patella dislocates every time the knee is flexed. The problem arises due to contracture of the quadriceps muscles. Soft tissue lengthening procedures such as quadriceps tendon lengthening are the m...
Background
A habitual patellar dislocation (HPD) is a rare condition in skeletally mature patients, especially for those with severe quadriceps contracture. Until now, no study has reported the effectiveness of tibial tubercle proximalization to lengthen the extensor mechanism in treating severe HPDs in skeletally mature patients.
Purpose
To descr...
Background: Congenital patellar dislocation (CPD) is a rare disorder which presents with hypoplastic and irreducible patellae. It is accompanied by flexion contracture of the knee joint, genu valgum, and external tibial rotation.
Case Report: A seven-year-old girl with CPD who was misdiagnosed as having cerebral palsy (CP) crouch gait and underwent...
Purpose
Langenskiöld described a reconstructive soft-tissue procedure for irreducible lateral congenital patellar dislocations. Paley further detailed the technique in the surgical management of congenital femoral deficiency. The aim of this study was to evaluate the outcomes of patients with congenital, chronic and recurrent patellar dislocations...
Citations
... The study by Zhang et al. [39] indicated that the efficacy of MPFL-R combined with DDFO was also satisfactory at FAA > 30°, and they found that when preoperative patients presented with a J-sign, patients with a preoperative high-grade J-sign had inferior clinical outcomes, more MPFL residual graft laxity, and greater residual patellar maltracking. In the treatment algorithm for RPD proposed by Frosch and Schmeling [44] isolated MPFL-R was advocated when patellar tracking was normal, regardless of the increased FAA, and DDFO was to be performed only in the presence of patellar maltracking. Zhang et al. [37] found in another secondary arthroscopic observation study of 102 patients who after isolated DDFO, patellar tracking improved in the majority of cases. ...
Background
Medial patellar ligament reconstruction (MPFL-R) in combination with derotational distal femoral osteotomy (DDFO) for treating recurrent patellar dislocation (RPD) in the presence of increased femoral anteversion is one of the most commonly used surgical techniques in the current clinical practice. However, there are limited studies on the clinical outcomes of MPFL-R in combination with DDFO to treat RPD in the presence of increased femoral anteversion.
Purpose
To study the role of MPFL-R in combination with DDFO in the treatment of RPD in the presence of increased femoral anteversion.
Methods
A systematic review was performed according to the PRISMA guidelines by searching the Medline, Embase, Web of Science, and Cochrane Library databases through June 1, 2023. Studies of patients who received MPFL-R in combination with DDFO after presenting with RPD and increased femoral anteversion were included. Methodological quality was assessed using the MINORS (Methodological Index for Nonrandomized Studies) score. Each study’s basic characteristics, including characteristic information, radiological parameters, surgical techniques, patient-reported outcomes, and complications, were recorded and analyzed.
Results
A total of 6 studies with 231 patients (236 knees) were included. Sample sizes ranged from 12 to 162 patients, and the majority of the patients were female (range, 67-100%). The mean age and follow-up ranges were 18 to 24 years and 16 to 49 months, respectively. The mean femoral anteversion decreased significantly from 34° preoperatively to 12° postoperatively. In studies reporting preoperative and postoperative outcomes, significant improvements were found in the Lysholm score, Kujala score, International Knee Documentation Committee score, and visual analog scale for pain. Postoperative complications were reported in all studies, with an overall reported complication rate of 4.7%, but no redislocations occurred during the follow-up period.
Conclusion
For RPD with increased femoral anteversion, MPFL-R in combination with DDFO leads to a good clinical outcome and a low redislocation rate. However, there was no consensus among researchers on the indications for MPFL-R combined with DDFO in the treatment of RPD.
... Valgus deformity of the lower limb frequently accompanies patellar instability, resulting in functional limitations, pain, and diminished quality of life [1,2]. The increased tibial tubercle-trochlear groove (TTTG) (>15 mm) is known as an anatomical risk factor for patellofemoral instability, as well as lateral patellofemoral arthritis [3][4][5]. ...
Purpose
While medial closing wedge distal femoral osteotomy (MCWDFO) has been used to address patella instability combined with valgus malalignment, its impact on patellofemoral parameters remains uncharted. Hence, this study seeks to establish a three‐dimensional (3D) planning of MCWDFO and measure its effect on the tibial tubercle ‐ trochlear groove distance (TTTG) through simulation and calculation.
Methods
MCWDFO with a stepwise increment of one‐degree varisation (1°–15°) was performed on 3D surface models of 14 lower extremities with valgus malalignment and 24 lower extremities with neutral alignment of the lower limb, resulting in a total of 608 simulations. Anatomic landmarks were employed to measure hip‐knee‐ankle angle (HKA), TTTG, and femoral torsion for each simulation. A mathematical formula was adopted to calculate TTTG changes following MCWDFO, and subsequently the mean simulated and calculated TTTG values were compared. Following a standardised protocol, MCWDFO was performed without rotational changes.
Results
MCWDFO exhibited an almost linear reduction in TTTG, at a rate of approximately −1.05 ± 0.13 mm per 1° of varisation, demonstrating a strong negative correlation (R = −0.83; p < 0.001). Limb alignment did not exert an influence on TTTG change; however, it correlated with tibial plateau width. The mean difference between the simulated and calculated TTTG values amounted to 0.03 ± 0.03 mm per 1° varisation ( p < 0.001).
Conclusion
The TTTG distance is linearly reduced by 1.05 mm for every 1° of varisation within the varus correction range of 0°–15° during MCWDFO. Patients with combined valgus and patellar instability may benefit from MCWDFO due to frequently pathological TTTG.
Level of Evidence
Level III, descriptive laboratory study.
... An 74% increase in total contact area was observed in our research with knee flexion from 30° to 60°. We believe that the reason for the small change in pressure may be the increase in the contact area as to the findings of other scholars [27,30,31]. The patellofemoral joint reduces the contact pressure of articular cartilage by increasing the contact area, which is a protective mechanism for the joint. ...
Purpose
To investigate the differences of patellofemoral joint pressure and contact area between the process of stair ascent and stair descent.
Methods
The finite element models of 9 volunteers without disorders of knee (9 males) to estimate patellar cartilage pressure during the stair ascent and the stair descent. Simulations took into account cartilage morphology from magnetic resonance imaging, joint posture from weight-bearing magnetic resonance imaging, and ligament model. The three-dimension models of the patella, femur and tibia were developed with the medical image processing software, Mimics 11.1. The ligament was established by truss element of the non-linear FE solver. The equivalent gravity direction (-z direction) load was applied to the whole end of femur (femoral head) according to the body weight of the volunteers, and the force of patella was observed. A paired-samples t-test or Wilcoxon rank sum test to make comparisons between stair ascent and stair descent. Statistical analyses were performed using SPSS 22.0 using a P value of 0.05 to indicate significance.
Results
During the stair descent (knee flexion at 30°), the contact pressure of the patella was 2.59 ± 0.06Mpa. The contact pressure of femoral trochlea cartilage was 2.57 ± 0.06Mpa. During the stair ascent (knee flexion at 60°), the contact pressure with patellar cartilage was 2.82 ± 0.08Mpa. The contact pressure of the femoral trochlea cartilage was 3.03 ± 0.11Mpa. The contact area between patellar cartilage and femoral trochlea cartilage was 249.27 ± 1.35mm² during the stair descent, which was less than 434.32 ± 1.70mm² during the stair ascent. The area of high pressure was located in the lateral area of patella during stair descent and the area of high pressure was scattered during stair ascent.
Conclusion
There are small change in the cartilage contact pressure between stair ascent and stair descent, indicating that the joint adjusts the contact pressure by increasing the contact area.
... In 2016, Schmeling and Frosch introduced a new classification for patellar instability and maltracking, with the aim of taking into consideration both clinical and radiological pathologies [23]. This classification is based on "instability" criteria, but it also introduces the evaluation of "maltracking" criteria and "loss of patellar tracking"; overall, these factors are evaluated via both clinical and radiological aspects. ...
The patellofemoral joint (PFJ) is a complex articulation between the patella and the femur which is involved in the extensor mechanism of the knee. Patellofemoral disorders can be classified into objective patellar instability, potential patellar instability, and patellofemoral pain syndrome. Anatomical factors such as trochlear dysplasia, patella alta, and the tibial tuberosity–trochlear groove (TT-TG) distance contribute to instability. Patellofemoral instability can result in various types of dislocations, and the frequency of dislocation can be categorized as recurrent, habitual, or permanent. Primary patellar dislocation requires diagnostic framing, including physical examination and imaging. Magnetic resonance imaging (MRI) is essential for assessing the extent of damage, such as bone bruises, osteochondral fractures, and medial patellofemoral ligament (MPFL) rupture. Treatment options for primary dislocation include urgent surgery for osteochondral fragments or conservative treatment for cases without lesions. Follow-up after treatment involves imaging screening and assessing principal and secondary factors of instability. Detecting and addressing these factors is crucial for preventing recurrent dislocations and optimizing patient outcomes.
... FAA, femoral anteversion angle; HPD, habitual patellar dislocation; LTI, lateral trochlear inclination; mLDFA, mechanical lateral distal femoral angle; MPTA, medial proximal tibial angle; RPD, recurrent patellar dislocation; SA, sulcus angle; TDI, trochlear depth index; TERA, tibial external rotation angle; TT-TG, tibial tubercle-trochlear groove distance; TT-TGa, tibial tubercle-trochlear groove angle; TT-TG/FW, tibial tubercle-trochlear groove distance/femoral width. patellofemoral dysbalance has been reported in many publications, [13][14][15]35,40,51 and this study appeared to justify this view. No significant difference was observed between the 2 groups. ...
Background
Recurrent patellar dislocation (RPD) and habitual patellar dislocation (HPD) in flexion are frequently encountered in children and adolescents.
Purpose
To compare the radiological features of RPD and HPD in children and adolescents.
Study Design
Cross-sectional study; Level of evidence, 3.
Methods
Imaging data were collected from patients aged 9 to 15 years who received surgical treatment for HPD or RPD at a single institution between June 2015 and September 2020. The prevalence of trochlear dysplasia, tibial tubercle lateralization, and lower limb rotational deformity was assessed through hip/knee/ankle computed tomography (CT) using the following quantitative indicators: trochlear depth index, lateral trochlear inclination, sulcus angle, tibial tubercle–trochlear groove (TT-TG) distance, ratio of TT-TG distance to femoral width, TT-TG angle, femoral anteversion angle, and tibial external rotation angle. The morphology of trochlea and patella were graded on knee CT using the Dejour and Wiberg classification. The Insall-Salvati index and Caton-Deschamps index were used to evaluate the height of the patella on lateral view radiographs. To evaluate lower limbs malalignment, the mechanical lateral distal femoral angle and medial proximal tibial angle were measured on weightbearing full-length radiographs. The collected data were analyzed and compared between the HPD and RPD groups.
Results
Enrolled were 15 patients (21 knees) diagnosed with HPD and 18 patients (22 knees) diagnosed with RPD. The age of first dislocation was significantly younger in the HPD group (7.6 ± 3.4 vs 11.2 ± 1.4 years; P = 0.003). Knees in the HPD group had a significantly higher proportion of Dejour type C dysplasia (57.1% vs 4.5%; P < .005) and Wiberg type 3 patella (66.7% vs 9.1%; P < .001). There were statistically significant differences between the groups in the trochlear depth index (HPD vs RPD: 1.1 ± 1.7 vs 2.2 ± 1.5 mm; P = .039), sulcus angle (170.3° ± 13.7° vs 157.3° ± 16.0°; P = .007), Insall-Salvati index (1.1 ± 0.2 vs 1.3 ± 0.2; P = .034), and tibial external rotation angle (31.3° ± 7.8° vs 38.4° ± 8.5°; P = .009).
Conclusion
Patients in the HPD group presented with poorer trochlear and patellar development, lower patellar height, and less tibial external rotation compared with patients in the RPG group.
... Dies ergibt sich durch die Kombination aus Patella baja, einem zentralen fibrösen Septum, welches die Patella nach lateral verdrängt, und einer wahrscheinlich konsekutiv einsetzenden Kontraktur des lateralen Retinakulums und des Musculus vastus lateralis [5]. Zu achten ist zusätzlich auf eine mögliche Hypoplasie der lateralen Femurkondyle, welche eine nach lateral ansteigende Kniegelenksebene bedingt und dadurch der Luxation in Beugestellung Vorschub leisten kann [2]. Dies war in den beiden dargestellten Fällen jedoch nicht der Fall. ...
... Fall 1Abb.1 8 In Extension (a) zentrierte Patella, die in Flexion (b) permanent nach lateral luxiert Abb.2 8 Typischer radiologischer Aspekt des Nail-Patella-Syndroms mit in Beugestellung luxierter hypoplastischer Patella (a) und sehr prominenter lateraler Trochlea (Stern) (a, b). Im MRT (c) kommt das zentrale Septum zur Darstellung (Pfeil) Abb. ...
Nail–patella syndrome (NPS) is an autosomal dominant hereditary disease which is
characterized by pathognomonic characteristics of the patellotrochlear morphology
leading to habitual flexion instability of the patella. This article describes the combined
surgical procedures to stabilize the patella based on two cases of nail–patella syndrome.
... This is due to, among other aspects, the variability of that injury and accompanying lesions. This absence of agreement may be the source of conflicting results across various treatment options [14]. Therefore, it is essential to develop a unified approach to ensure that patients receive the best possible medical standard [3]. ...
... This observation was confirmed by multiple biomechanical investigations that demonstrated direct alterations of patellar tracking when certain risk factors were present [6][7][8][9][10]. On the basis of these findings, modern surgical approaches are aimed at identifying and addressing all relevant pathologies in the affected knee [11][12][13]. In the recent literature, several clinical studies have examined the postoperative success of individualized patellofemoral surgery, and most of these studies reported improved patient-reported outcome measures (PROMs) and low redislocation rates [14][15][16][17][18][19][20][21]. ...
... Surgical realignment procedures were indicated and performed by three experienced orthopedic surgeons (MK, KF, and JF) on the basis of the clinical and radiological findings, following an algorithmic treatment approach (Figures 1 and 2) [12,26]. The first radiological examination was performed prior to the planned surgery. ...
... Diagnostic arthroscopy was performed at the beginning of each procedure t low for the assessment patellofemoral maltracking and to check for any concomitant tilaginous) injuries ( Figure 3). After arthroscopy, surgical correction of patellar maltracking was performed in cordance with the underlying pathology [12]. ...
Persisting patellar maltracking following surgical realignment often remains unseen. The aim of this study was to analyze the effects of realignment procedures on patellofemoral kinematics in patients with patellofemoral instability (PFI) and patellofemoral maltracking (PM) by using dynamic magnetic resonance imaging (MRI). Patients planned for surgical patellar realignment due to PFI and a clinically and radiologically apparent PM between December 2019 and May 2022 were included. Patients without PM, limited range of motion, joint effusion, or concomitant injuries were excluded. Dynamic mediolateral translation (dMPT) and patella tilt (dPT) were measured preoperatively and three months postoperatively. In 24 patients (7 men, 17 women; mean age 23.0 years), 10 tibial tubercle transfers, 5 soft tissue patella tendon transfers, 6 trochleoplasties, 3 lateral lengthenings, 1 varizating distal femoral osteotomy (DFO), and 1 torsional DFO were performed. At final follow-up, dMPT (from 10.95 ± 5.93 mm to 4.89 ± 0.40 mm, p < 0.001) and dPT (from 14.50° ± 10.33° to 8.44° ± 7.46°, p = 0.026) were significantly improved. All static radiological parameters were corrected to physiological values. Surgical patellar realignment contributed to the significant improvement of patellofemoral kinematics, with an approximation to normal values. The postoperative application of dynamic MRI allowed for a quantification of the performed correction, allowing for a postoperative control of success.
... Patellar-femoral joint instability can be the result of unphysiological movement of the patella within the trochlear groove (known as maltracking) resulting in recurrent patellar dislocation or subluxation [1] and could cause cartilage damage to the joint surface [2]. Examinations of the patellar-femoral joint are diverse and include physical examination, radiography, computed tomography, magnetic resonance imaging, and arthroscopy. ...
This study evaluated the accuracy of tangential axial radiography of the patellar and femoral joint using an auxiliary device based on three image evaluation criteria, which we named the patellofemoral joint radiography auxiliary device (PJR). To compare the PJR method with conventional radiographic methods, such as Laurin, Merchant, and Settegast, a whole-body phantom (PBU-31) was used and three image evaluation items were set. The radiographic method, the smallest inclination of the patellar and showed the best half lateral image of the patella, is Settegast, and the measurement is 9.40. The second-best PJR measurement is 9.97, and the difference between the two measures is 5.76% (p=0.001). The radiographic method showing the image with the largest distance between the patellar and femoral joint space is PJR which a measurement is 12.35. The second best Merchant measure is 10.55, and the difference between the two measures is 14.54% (p=0.001). The method in which the two bones were well overlapped (i.e., evaluate the distortion of the image by measured as the distance between the femoral trochlear groove and the tibial tuberosity) is the PJR and the measurement is −0.37. The second-best Merchant measure is 3.93, and the difference between the two measures is 91.4% (p=0.001). The Settegast has the image with the smallest inclination of the patella, but the PJR has the image that best describes the patellar–femoral joint and the least distortion of the image. As a result of the comprehensive evaluation, when using PJR, bending the knee by 40° and setting a 140° angle between the long axis of the femur and the long axis of the lower leg were considered to be the most beneficial conditions. Therefore, we propose the use of PJR for tangential axial radiography of the patellar–femoral joint.
... Several authors reported good to excellent clinical results after derotational femoral osteotomy [22,23] but this procedure is not common in part because the indications are not yet clearly defined. In our experience, the ideal indication is a type 3e in Frosch's classification of patellar instability corresponding to a patellar maltracking with pain or patellar instability and torsional deformity [24]. The choice of the surgical approach, the bone cuts, associated deformity correction and other procedures remain challenging. ...
Background
Rotational malalignment deformities of the lower limb in adults mostly arise from excessive femoral anteversion and/or excessive external tibial torsion. The aim of this study was to assess the correction accuracy of a patient specific cutting guides (PSCG) used in tibial and femoral correction for lower-limb torsional deformities.
Methods
Forty knees (32 patients) were included prospectively. All patients had patellofemoral pain or instability with torsional malalignment for which a proximal tibial (HTO) or distal femoral (DFO) or a double-level osteotomy (DLO) had been performed. Accuracy of the correction between the planned and the postoperative angular values including femoral anteversion, tibial torsion, coronal and sagittal alignment were assessed after tibial and/or femoral osteotomy.
Results
Forty knees were included in this study. In cases of HTO, the correction accuracy obtained with PSCG was 1.3 ± 1.1° for tibial torsion (axial plane), 0.8 ± 0.7° for MPTA (coronal plane) and 0.8 ± 0.6° for PPTA (sagittal plane). In cases of DFO, the correction accuracy obtained with PSCG was 1.5 ± 1.4° for femoral anteversion (axial plane), 0.9 ± 0.9° for LDFA (coronal plane) and 0.9 ± 0.9° for PDFA (sagittal plane). The IKSG was improved from 58.0 ± 13.2° to 71.4 ± 10.9 (p = 0.04) and the IKSF from 50.2 ± 14.3 to 87.0 ± 6.9 (p < 0.001).
Conclusions
Using the PSCG for derotational osteotomy allows excellent correction accuracy in all the three planes for femoral and tibial torsional deformities associated with patellofemoral instability.
Level of clinical evidence II, prospective cohort study.
