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Posterior humeral head subluxation measurement (b/[a 1 b]). The index of subluxation is the ratio between the part of the head posterior to the midpoint of the glenoid (b), and the greatest head diameter (a 1 b).
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![Figure 2. Posterior humeral head subluxation measurement (b/[a 1 b])....](profile/Xinning-Li/publication/306127772/figure/fig3/AS:667789920587776@1536224932029/Posterior-humeral-head-subluxation-measurement-b-a-1-b-The-index-of-subluxation-is_Q320.jpg)
Background:
Posterior shoulder instability is less common and potentially more difficult to diagnose clinically and radiographically compared with anterior shoulder instability. Radiographic findings including posterior labral tears, increased retroversion, presence of glenoid dysplasia, and increased capsular area are associated with symptomatic...
Context in source publication
Context 1
... correspondence to MAJ Joseph W. Galvin, DO, Orthopaedic Surgery Service, Department of Surgery, Madigan Army Medical Center, 9040 Jackson Avenue, Tacoma, WA 98431, USA (email: joseph.w.galvin@gmail.com). Posterior humeral head subluxation was measured according to the methods described initially by Papilion and Larry 12 and more recently by Walch et al. 15 The index of subluxation is the ratio between the part of the head pos- terior to the midpoint of the glenoid and the greatest head diameter (Figure 2). ...
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Background
SLAP lesions of the shoulder are challenging to diagnose by clinical means alone. Interpretation of MR images requires knowledge of the normal appearance of the labrum, its anatomical variants, and the characteristic patterns of SLAP lesions. In general, high signal extending anterior and posterior to the biceps anchor is the hallmark of...
Posterior shoulder instability is a rare clinical condition that encompasses different degrees of severity including various possible pathologies involving the labrum, capsule, bony lesions, and even locked posterior dislocation. When focusing on soft tissue involvement, the diagnosis of posterior instability may be difficult to make because freque...
Citations
... [2][3][4] Risk factors for acute (mostly anterior) dislocation have been identified and include age, sex, sport participation, immobilization protocol, and glenoid shape. [5][6][7][8][9][10][11][12] Instability associated with microtrauma or atraumatic instability is more difficult to diagnose and may present with a range of symptoms from the feeling of looseness or instability to humeral subluxation with immediate reduction. 13 The incidence of glenohumeral instability is therefore more difficult to measure. ...
... Two variations, humeral containing angle >64 degrees 8 and coracohumeral interval, 10 had minimal association with risk yielding OR's of <1.20 in those with anterior dislocation and/or subluxation while there was a small association between glenoid dysplasia and injury ((OR = 2.84, CI: (1.14, 7.09) in those with posterior dislocation and/or subluxation. 7 Regarding glenoid retroversion, three studies 7,10,37 included this variation. Two studies resulted nearly identical OR's of 1.15 7 and 1.17 37 (CI: 1.14, 1.16 and CI: 1.03, 1.34) in those with posterior dislocation and/or subluxation while one determined there to be a small risk ((OR = 4.83, (CI: 1.75, 13.33)) in those with anterior dislocation and/or subluxation. ...
Background
Shoulder instabilities constitute a large proportion of shoulder injuries and have a wide range of presentations. While evidence regarding glenohumeral dislocations and associated risk factors has been reported, less is known regarding the full spectrum of instabilities and their risk factors.
Purpose
The purpose of this systematic review was to identify modifiable risk factors to guide patient management decisions with regards to implementation of interventions to prevent or reduce the risk of shoulder instability.
Study Design
Systematic Review
Methods
A systematic, computerized search of electronic databases (CINAHL, Cochrane, Embase, PubMed, SportDiscus, and Web of Science) was performed. Inclusion criteria were: (1) a diagnosis of shoulder instability (2) the statistical association of at least one risk factor was reported, (3) study designs appropriate for risk factors, (4) written in English, and (5) used an acceptable reference standard for diagnosed shoulder instability. Titles and abstracts were independently screened by at least two reviewers. All reviewers examined the quality studies using the Newcastle-Ottawa Scale (NOS). At least two reviewers independently extracted information and data regarding author, year, study population, study design, criterion standard, and strength of association statistics with risk factors.
Results
Male sex, participation in sport, hypermobility in males, and glenoid index demonstrated moderate to large risk associated with first time shoulder instability. Male sex, age \<30 years, and history of glenohumeral instability with concomitant injury demonstrated moderate to large risk associated with recurrent shoulder instability.
Conclusion
There may be an opportunity for patient education in particular populations as to their increased risk for suffering shoulder instability, particularly in young males who appear to be at increased risk for recurrent shoulder instability.
Level of Evidence
Level III
... Normal glenoid version is essentially 0°, often with slight anteversion or retroversion varying less than 10° in either direction [44]. Increased glenoid retroversion may predispose patients to posterior shoulder instability, with higher degrees of retroversion conveying increased risk [1,[45][46][47]. In a prospective study of 714 military cadets, Owens et al. found glenoid retroversion to be an independent risk factor for posterior shoulder instability and that for every 1° of increased glenoid retroversion, the risk of posterior shoulder instability increased by 17% [1]. ...
Purpose of Review
Posterior shoulder instability is an uncommon but important cause of shoulder dysfunction and pain which may occur as the result of seizure, high energy trauma, or repetitive stress related to occupational or sport-specific activities. This current review details the imaging approach to the patient with posterior shoulder instability and describes commonly associated soft tissue and bony pathologies identified by radiographs, CT, and MR imaging.
Recent Findings
Advances in MR imaging technology and techniques allow for more accurate evaluation of bone and soft tissue pathology associated with posterior shoulder instability while sparing patients exposure to radiation.
Summary
Imaging can contribute significantly to the clinical management of patients with posterior shoulder instability by demonstrating the extent of associated injuries and identifying predisposing anatomic conditions. Radiologic evaluation should be guided by clinical history and physical examination, beginning with radiographs followed by CT and/or MRI for assessment of osseous and soft tissue pathology. Synthesis of a patient’s clinical history, physical exam findings, and radiologic examinations should guide clinical management.
... Many studies have suggested a correlation between an increased glenoid retroversion and the risk of developing dynamic PSI. For instance, Galvin et al. found that patients with posterior glenohumeral instability (PGHI) exhibited an average glenoid retroversion of − 8.16° during MRI analysis, whereas the control group had a retroversion of − 2.9° [27]. Owens et al. took this concept further by postulating that for every degree of increased retroversion, the risk of PSI increased by 17% [28]. ...
... A deviation of 6.3° in the Friedman method falls within acceptable measurement tolerances, as confirmed by Friedman et al. who reported a range of − 12 to 14° in their control cohort [19]. This suggests that the examined patient cohort did not exhibit osteoarthritic changes in the glenoid, which, in other studies, could be linked to increased retroversion [27,28,30]. We concluded that the PSI in our cohort primarily originated from traumatic events. ...
Purpose
This study aims to assess the clinical outcomes in the management of post-traumatic posterior shoulder instability (PSI) with a focus on the decision-making process for operative and conservative treatments.
Introduction
PSI can result from traumatic events, impacting a patient’s quality of life. This study delves to better indicate decision-making for operative indication of post-traumatic PSI patients.
Methods
Patients who sustained posterior shoulder dislocations were selected from a single surgeon’s database within a five-year period. Cases of degenerative or genetically caused PSI were excluded, resulting in a cohort of 28. Patients were initially managed conservatively but indicated for surgery if they were unable to actively stabilize the shoulder or exhibited bony or cartilage defects confirmed through imaging. If conservative treatment did not yield significant improvements, it was classified as a failure, and operative intervention was recommended. The WOSI Score, ROM, and X-ray were employed to evaluate the success of treatment.
Results
Out of the 28 patients, 11 received conservative, seven immediate surgeries, and ten transitioned from conservative to operative treatment. The overall success rate showed 25 good to excellent results. In the persistent conservative treatment group, the initial WOSI score was significantly lower compared to the operative group.
Conclusion
This study suggests that post-traumatic PSI can be successfully managed conservatively with initial low clinical symptoms (low WOSI score) and in the absence of absolute indications for operative treatment. When surgery is necessary, arthroscopic procedures proved effective in achieving good to excellent results in 16 out of 17 cases.
... [2][3][4]6,10,12,15,[19][20][21] Prior studies have identified radiographic variables significantly associated with posterior shoulder instability and outcomes of APCLR including glenoid retroversion, chondrolabral version, glenoid dysplasia, glenoid width, posterior capsular area, and posterior acromial morphology. 3,7,[15][16][17] Meyer et al performed a retrospective study of patients with unidirectional posterior ...
Background
Prior evidence has identified specific posterior acromial morphology as significantly associated with unidirectional posterior shoulder instability. The purpose of this study is to determine the influence of posterior acromial morphology on the outcomes of arthroscopic posterior capsulolabral repair (APCLR) for unidirectional posterior shoulder instability. Additionally, we sought to determine the influence of posterior acromial morphology on the rate and time to return to pushups following APCLR.
Methods
We performed a retrospective review of prospectively collected data. The study included consecutive patients undergoing APCLR. Data collected included demographics, radiographic measurements including posterior acromial height (PAH) and posterior acromial tilt on preoperative scapular-Y radiographs, and patient-reported outcome measures at the preoperative and postoperative visits. In addition, starting at 6 months postoperative, patients were asked if they could perform pushups defined as at least 10 repetitions. At the final follow-up, we collected the number of pushups patients were able to perform.
Results
Thirty-two consecutive patients underwent APCLR with a mean follow-up of 26 months (range, 12-41). Significant improvement from preoperative to 2 years postoperative was demonstrated in Subjective Shoulder Value (50-85), VAS (6-2.5), American Shoulder and Elbow Surgeons (48 to 83), and Western Ontario Shoulder Instability (WOSI) (1437-777), P = .001. The recurrent instability rate was 3/32 (9%). Patients with PAH > 23 (N = 17) had a recurrent instability rate of 18% (3/17) versus PAH ≤ 23 (N = 15) 0% (0/15), worse WOSI scores (P = .41), and a lower number of pushups (P = .48). The percentage of patients reporting the ability to perform pushups was (6 months/1 year/2 years) (50%/78%/95%). The mean number of pushups reported at the final follow-up was 33 (range, 1-60).
Discussion
Following APCLR, approximately 50% of patients resume pushups at 6 months postoperatively, and 80% return at 1 year. Patients reported performing a mean of 33 pushups following APCLR at the final follow-up. Patients with a PAH greater than 23 on preoperative scapular-Y radiographs had a higher rate of recurrent posterior instability, worse WOSI scores, and lower return to pushups; however, the results did not meet statistical significance. Therefore, future larger studies are needed to determine if posterior acromial morphology is independently associated with worse outcomes and increased recurrent instability rates following APCLR.
... Bu sebeplerden MRA labral ve kapsüler patolojiyi ayrıntılı gösterdiği için invaziv olmayan en güvenilir tanısal yöntemdir. [11] ...
... The determination of the scapular axis (Friedman line) on MRI for measurement of glenoid version or humeral head subluxation has been described before [17,18]. Even though measurements in this study were conducted using CT scans, it can be assumed, that this method can be translated to MRI which typically also offers a limited FOV and comparable bony landmarks identification [19,20]. ...
Background:
Scapulothoracic orientation, especially scapular internal rotation (SIR) may influence range of motion in reverse total shoulder arthroplasty (RTSA) and is subjected to body posture. Clinical measurements of SIR rely on apical bony landmarks, which depend on changes in scapulothoracic orientation, while radiographic measurements are often limited by the restricted field of view (FOV) in CT scans. Therefore, the goal of this study was (1) to determine whether the use of CT scans with a limited FOV to measure SIR is reliable and (2) if a clinical measurement could be a valuable alternative.
Methods:
This anatomical study analyzed the whole-body CT scans of 100 shoulders in 50 patients (32 male and 18 female) with a mean age of 61.2 ± 20.1 years (range 18; 91). (1) CT scans were rendered into 3D models and SIR was determined as previously described. Results were compared to measurements taken in 2D CT scans with a limited FOV. (2) Three apical bony landmarks were defined: (the angulus acromii (AA), the midpoint between the AA and the coracoid process tip (C) and the acromioclavicular (AC) joint. The scapular axis was determined connecting the trigonum scapulae with these landmarks and referenced to the glenoid center. The measurements were repeated with 0°, 10°, 20°, 30° and 40° anterior scapular tilt.
Results:
Mean SIR was 44.8° ± 5.9° and 45.6° ± 6.6° in the 3D and 2D model, respectively (p < 0.371). Mean difference between the measurements was 0.8° ± 2.5° with a maximum of 10.5°. Midpoint AA/C showed no significant difference to the scapular axis at 0° (p = 0.203) as did the AC-joint at 10° anterior scapular tilt (p = 0.949). All other points showed a significant difference from the scapular axis at all degrees of tilt.
Conclusion:
2D CT scans are reliable to determine SIR, even if the spine is not depicted. Clinical measurements using apical superficial scapula landmarks are a possible alternative; however, anterior tilt influenced by posture alters measured SIR.
... Glenoid version was measured on the axial MRI or CT slices at the midglenoid point using the Friedman technique. 12,13 A straight line bisected the glenoid fossa and extended to the most medial edge of the scapula. A second line was drawn perpendicular to this line (line A). ...
Background
The pattern of glenoid bone loss (GBL) in anterior glenohumeral instability is well described. It was recognized recently that posterior GBL after instability has a posteroinferior pattern.
Purpose/Hypothesis
The purpose of this study was to compare GBL patterns in a matched cohort of patients with anterior versus posterior glenohumeral instability. The hypothesis was that the GBL pattern in posterior instability would be more inferior than the GBL pattern in anterior instability.
Study Design
Cohort study; Level of evidence, 3.
Methods
In this multicenter retrospective study, 28 patients with posterior instability were matched with 28 patients with anterior instability by age, sex and number of instability events. GBL location was defined using a clockface model. Obliquity was defined as the angle between the long axis of the glenoid and a line tangent to the GBL. Superior and inferior GBL were measured as areas and defined relative to the equator. The primary outcome was the 2-dimensional characterization of posterior versus anterior GBL. The secondary outcome was a comparison of the posterior GBL patterns in traumatic and atraumatic instability mechanisms in an expanded cohort of 42 patients.
Results
The mean age of the matched cohorts (n = 56) was 25.2 ± 9.87 years. The median obliquity of GBL was 27.53° (interquartile range [IQR], 18.83°-47.38°) in the posterior cohort and 9.28° (IQR, 6.68°-15.75°) in the anterior cohort ( P < .001). The mean superior-to-inferior bone loss ratio was 0.48 ± 0.51 in the posterior cohort and 0.80 ± 0.55 ( P = .032) in the anterior cohort. In the expanded posterior instability cohort (n = 42), patients with traumatic injury mechanism (n = 22), had a similar GBL obliquity compared to patients with an atraumatic injury mechanism (n = 20) (mean, 27.73° [95% CI, 20.26°-35.20°] vs 32.20° [95% CI, 21.27°-43.14°], respectively) ( P = .49).
Conclusion
Posterior GBL occurred more inferiorly and at an increased obliquity compared with anterior GBL. This pattern is consistent for traumatic and atraumatic posterior GBL. Bone loss along the equator may not be the most reliable predictor of posterior instability, and critical bone loss may be reached more rapidly than a model of loss along the equator may predict.
... 3 Radiographic and advanced imaging parameters such as increased glenoid retroversion, glenoid dysplasia, increased posterior capsular area, and increased posterior acromial height and decreased posterior acromial slope are associated with posterior shoulder instability and can aid clinicians in the diagnosis. [4][5][6][7][8][9][10][11] Physical examination, however, remains the most critical step in the diagnosis of posterior shoulder instability. Prior tests for diagnosing posterior shoulder instability include the jerk test, Kim test, push-pull test, Porcellini test, and posterior load-and-shift test. ...
Posterior shoulder instability is becoming increasingly recognized in young active patient populations. Diagnosing posterior instability can be challenging because patients commonly present with a complaint of pain without a history of a dislocation or subluxation event. Additionally, a posterior labral tear is not always clearly visualized on advanced imaging studies. As such, physical examination is critical to the diagnosis. We report a simple physical examination maneuver for the diagnosis of symptomatic posterior shoulder instability. The thumb test attempts to replicate a posterior bone block procedure, helping to re-establish stability and relieve pain. The examiner places his or her thumb over the posterior glenohumeral joint line while the patient actively forward elevates the affected arm overhead. Improvement in pain and stability with this maneuver is diagnostic for symptomatic posterior shoulder instability. This test augments current physical examination maneuvers to assist with correctly diagnosing posterior shoulder instability.
... Furthermore, MRI interpretation has previously been reported to have a large amount of variability, specifically in rotator cuff 30,34 and labral pathology. 8,13,39 MRI scans in this study were reviewed by experts in the field of musculoskeletal radiology; however, the inherent variability in MRI interpretation may limit diagnostic accuracy and comparison to other MRI studies. Also, differences in MRI technique between this study, which used a 3.0-T field strength scanner, and many other studies that used 1.5-T field strength are difficult to quantify and define. ...
Background
The prevalence of findings on shoulder magnetic resonance imaging (MRI) is high in asymptomatic athletes of overhead sports.
Purpose/Hypothesis
The purpose of this study was to determine the prevalence of atypical findings on MRI in shoulders of asymptomatic, elite-level climbers and to evaluate the association of these findings with clinical examination results. It was hypothesized that glenoid labrum, long head of the biceps tendon, and articular cartilage pathology would be present in >50% of asymptomatic athletes.
Study Design
Cross-sectional study; Level of evidence, 3.
Methods
A total of 50 elite climbers (age range, 20-60 years) without any symptoms of shoulder pain underwent bilateral shoulder examinations in addition to dedicated bilateral shoulder 3-T † MRI. Physical examinations were performed by orthopaedic sports medicine surgeons, while MRI scans were interpreted by 2 blinded board-certified radiologists to determine the prevalence of abnormalities of the articular cartilage, glenoid labrum, biceps tendon, rotator cuff, and acromioclavicular joint.
Results
MRI evidence of tendinosis of the rotator cuff, subacromial bursitis, and long head of the biceps tendonitis was exceptionally common, at 80%, 79%, and 73%, respectively. Labral pathology was present in 69% of shoulders, with discrete labral tears identified in 56%. Articular cartilage changes were also common, with humeral pathology present in 57% of shoulders and glenoid pathology in 19% of shoulders. Climbers with labral tears identified in this study had significantly increased forward elevation compared with those without labral tears in both active ( P = .026) and passive ( P = .022) motion.
Conclusion
The overall prevalence of intra-articular shoulder pathology detected by MRI in asymptomatic climbers was 80%, with 57% demonstrating varying degrees of glenohumeral articular cartilage damage. This high rate of arthritis differs significantly from prior published reports of other overhead sports athletes.
... Analogous to other studies, we also found an increased incidence of glenoid retroversion in the patients with B2 instability. 5,15,17,19,31 The median glenoid version of all patients measured with the vault method was 14.8 . Meanwhile, the glenohumeral index was normal being 52% (Table II). ...
Purpose
To validate glenoid cartilage lesions as a negative prognostic factor, and to define a new image-based preoperative evaluation method to identify surgical candidates for arthroscopic labral refixation with suture anchors in posterior shoulder instability.
Methods
26 patients who underwent arthroscopic posterior labral repair for shoulder instability were evaluated. Only patients with structural dynamic posterior instability were included. We evaluated on preoperative magnetic resonance arthrogram: glenoid version, humeral head subluxation, type of capsular insertion and the cartilage lesions using the new Cartilage Wear Index. Two subgroups were analyzed with regards to the preoperative Cartilage Wear Index and shoulder outcome scores: Single Assessment Numerical Evaluation (SANE) and Western Ontario Shoulder Instability Index (WOSI).
Results
Median age at operation was 28 (interquartile range 21-33). Median overall postoperative outcome assessment demonstrated a SANE of 90 and WOSI of 385. The median Cartilage Wear Index was 1.02. Subgroup analysis revealed worse median WOSI and SANE scores in patients with CWI>1.02 and a strong correlation between high preoperative Cartilage Wear Index and higher postoperative WOSI score (R=0.58 p=0.038).
Conclusion
The Cartilage Wear Index can be useful to identify patients that might obtain better outcomes when treated with arthroscopic labral repair in posterior shoulder instability.
