Imaging techniques for the evaluation of glenohumeral instability

Assessment and diagnosis of non-traumatic shoulder instability: A scoping review

Background

Given its complexity, there is no consensus regarding the assessment of non-traumatic shoulder instability (NTSI) to this day. We, therefore, conducted a scoping review to map the existing white and grey literature regarding diagnostic and assessment tools for the NTSI population.

Method

We followed the Arksey and O'Malley five-stage guideline for the conduct of scoping reviews and searched through 12 electronic databases for English-language articles and reviews from 2000 to 2024 related to NTSI's diagnosis and assessment tools.

Results

Among the 3426 identified studies, 58 were included (describing 59 different interventions). Case-control studies (43.1%, 25/58) and narrative reviews (34.5%, 20/58) were the most prevalent. Diagnostic imaging was the most studied intervention (35.6%, 21/59). Twenty-seven studies specified a direction of instability, of which 59% (16/27) were multidirectional instability. Non-traumatic shoulder instability often affects young individuals, with complex symptoms, including neuromotor deficits, muscular imbalances and kinematic alterations, involving psycho-behavioural and somatosensory components.

Discussion

Non-traumatic shoulder instability's aetiologies and clinical manifestations are multifactorial. The prevalence and incidence of this dysfunction are probably underestimated. Clinical history is crucial to retrace a complex and chronic dysfunction. The use of orthopaedic shoulder tests and the routine use of imaging currently appear to have limited relevance as a first-line approach.

Role of Magnetic Resonance Imaging (MRI) in the Diagnosis of Rotator Cuff Injuries and Correlation With Arthroscopy Findings

BACKGROUND AND AIM

The prevalent cause of shoulder pain is rotator cuff tears (RCT), which induce profound discomfort and morbidity. Hence, their detection and appropriate management become important to alleviate morbidity and enhance quality of life. Imaging has an important role in the diagnosis of such patients to guide for further management. A wide array of radiological approaches has been explored for the detection of RCT. The study aimed to assess the sensitivity (SN) and specificity (SP) of regular magnetic resonance imaging (MRI) in the diagnosis and characterization of RCT and furthermore to link the results of MRI with the arthroscopy findings. The limitations and pitfalls if any with MRI patients presenting were also addressed.

MATERIALS AND METHODS

The study was a diagnostic evaluation study conducted at the Department of Radiodiagnosis, Muslim Educational Society (MES) Medical College, Perinthalmanna, India, among individuals with RCT between December 1, 2015, and May 31, 2017. Patients who were referred for MRI and then taken up for arthroscopy were included. The findings for each tendon of rotator cuff on MRI were contrasted with that of arthroscopy, and the percentage of agreement was calculated. Additional findings relevant to the study were also noted. SN, SP, positive predictive value (PPV), and negative predictive value (NPV) of MRI were determined by taking arthroscopic findings as the gold standard.

RESULTS

The study was comprised of 36 patients assessed using MRI and arthroscopy for RCT. The study participants ranged in age from 31 to 70 years, with a mean of 52.69±8.86 years. The majority of the patients (69.4%) were between the ages of 41 and 60 years. MRI had 100% SN and SP for full-thickness supraspinatus (SS) tear, 50% SN and 100% SP for partial-thickness SS tear, 100% SN and 80% SP for full-thickness infraspinatus (IS) tear, 75% SN and 80% SP for partial-thickness IS tear, and 95% SN and 86.6% SP for subscapularis (SC) tear.

CONCLUSION

The MRI RCT investigation had a high SN, SP, and PPV compared to arthroscopy. The most frequently involved tendon reported in the present study was SS (n=35; 97.22%) followed by IS (n=32; 88.88%) and SC (n=22; 61.11%). The teres minor tendon was least commonly affected (n=0). Moreover, 61.11% (n=22) of the patients had joint effusion, 41.66% (n=15) had subacromial-subdeltoid bursal effusion, and 27.77% (n=10) had subcoracoid effusion, suggesting that RCT include joint effusion or bursal fluid. Acromioclavicular (AC) joint hypertrophy was found in 53% (n=19) of the patients, and 90% (n=17) were over 45 years old, indicating an association between age, AC joint hypertrophy, and RCT. Therefore, MRI has a good SN and SP for detecting various RCT. Therefore, it could be used to investigate a suspected RCT and should be considered a near-reference standard to arthroscopy for RCT diagnosis.

Posterior Shoulder Instability in Tennis Players: Aetiology, Classification, Assessment and Management

Background

Micro-traumatic posterior shoulder instability (PSI) is an often missed and misdiagnosed pathology presenting in tennis players. The aetiology of micro-traumatic PSI in tennis players is multifactorial, including congenital factors, loss of strength and motor control, and sport-specific repetitive microtrauma. Repetitive forces placed on the dominant shoulder, particularly combinations of flexion, horizontal adduction, and internal rotation contribute to the microtrauma. These positions are characteristic for kick serves, backhand volleys, and the follow-through phase of forehands and serves. The aim of this clinical commentary is to present an overview of the aetiology, classification, clinical presentation, and treatment of micro-traumatic PSI, with a particular focus on tennis players.

Level of Evidence

5.

Kinematics and biomechanical validity of shoulder joint laxity tests as diagnostic criteria in multidirectional instability

BACKGROUND

Clinical laxity tests are commonly used together to identify individuals with multidirectional instability (MDI). However, their biomechanical validity in distinguishing distinct biomechanical characteristics consistent with MDI has not been demonstrated.

OBJECTIVE

To determine if differences in glenohumeral (GH) joint laxity exist between individuals diagnosed with multidirectional instability (MDI) and asymptomatic matched controls without MDI.

METHODS

Eighteen participants (9 swimmers with MDI, 9 non-swimming asymptomatic matched controls without MDI) participated in this observational study. Participants were classified as having MDI with a composite laxity score from three laxity tests (anterior/posterior drawer and sulcus tests). Single plane dynamic fluoroscopy captured joint motion with 2D-3D joint registration to derive 3D joint kinematics. Average GH translations occurring during the laxity tests were compared between groups using an independent sample's t-test. The relationship of composite laxity scores to overall translations was examined with a simple linear regression. Differences of each laxity test translation between groups were analyzed with a two-way repeated measures ANOVA.

RESULTS

Mean composite translations for swimmers were 1.7 mm greater (p = 0.04, 95% Confidence Interval (CI): 0.1, 3.3 mm) compared to controls. A moderate association occurred (r² = 0.40, p = 0.005) between composite laxity scores and composite translation. Greater translations for the posterior drawer (-2.4 mm, p = 0.04, 95% CI: -0.1, -4.6) and sulcus tests (-2.7 mm, p = 0.03, 95% CI: -0.3, -5.0) existed in swimmers compared to controls.

CONCLUSION

Significant differences in composite translation existed between symptomatic swimmers with MDI and asymptomatic control participants without MDI during GH joint laxity tests. The results provide initial biomechanically based construct validity for the clinical criteria used to identify individuals with MDI.

Anterior Glenohumeral Instability in the Adolescent Athlete

Glenohumeral instability is multifactorial and has both static and dynamic elements. The initial management of first-time dislocations has become increasingly controversial, although recent evidence supports operative treatment for adolescents who participate in contact sports. Risk factors for recurrent glenohumeral instability include adolescent age, hyperlaxity, glenoid bone loss, off-track Hill-Sachs lesions, and fixation with <=3 anchors. High rates of return to sport can be expected when the surgical plan is tailored to individual pathology.

Shoulder Position During Magnetic Resonance Arthrogram Significantly Affects Capsular Measurements

PURPOSE

To determine whether change in shoulder position between internal rotation (IR) and external rotation (ER) during magnetic resonance arthrography (MRA) affects previously defined capsular measurements and to determine the utility of rotation in the diagnosis of instability.

METHODS

A retrospective study was conducted of patients who received a shoulder MRA with humeral IR and ER views. Patients with an arthroscopically confirmed diagnosis of instability and those with clinically stable shoulders, no history of instability, and no MRA findings of instability were identified and compared. Humeral rotation, glenoid retroversion, humeral head subluxation, capsular length, and capsular area using axial sequences of IR and ER views were recorded. Analysis compared IR, ER, and Δ capsular measurements between groups using independent t tests and univariate and multivariate regression.

RESULTS

Thirty-one subjects who were diagnosed with instability were included, along with 28 control subjects. Capsular length, capsular area, and humeral subluxations were significantly greater with ER compared with IR views (P < .001, P < .001, P < .001). Patients with instability displayed greater ER capsular length (P = .0006) and ER capsular area (P = .005) relative to controls. Multivariate logistic regression identified age, weight, sex, ER capsular length, and retroversion to be significant predictors of instability. ER capsular length independently predicts instability with 86% sensitivity and 84% specificity. Interobserver reliability using the intraclass correlation coefficient was rated good or excellent on all measurements.

CONCLUSION

Variance in humeral rotation during shoulder MRA significantly affects capsular measurements. Rotational views increase the utility of capsular measurements when assessing for instability, particularly capsular length and capsular area. The implementation of ER positioning enhances the ability to examine capsular changes of the shoulder joint and can assist in the diagnosis of instability.

LEVEL OF EVIDENCE

III, retrospective comparative study.

The V-Sign: A Simple Radiographic Sign of Shoulder Subluxation

Introduction

Shoulder subluxation is a common finding associated with orthopedic pathology. This study assesses the inter- and intra-observer reliability of a new radiographic sign used to identify glenohumeral subluxation.

Methods

Shoulders of 55 consecutive patients presenting with shoulder pain were reviewed for the presence of a “V-sign”. Three shoulder surgeons reviewed all radiographs at three separate time periods in a randomized fashion. Inter- and intra-observer reliabilities were calculated.

Results

The V-sign was identified in 26 (47%) shoulders. Intra-rater reliability was satisfactory for all the three surgeons, with kappa values of 0.85, 0.78, and 0.77, respectively. Inter-rater reliability was similarly satisfactory, with a value of 0.71. The surgeons demonstrated 100% agreement on the direction of subluxation when a V-sign was documented.

Discussion

The V-sign is a reproducible radiographic sign that can be used to detect glenohumeral subluxation in patients presenting with shoulder pain.

Are radiologists superior to orthopaedic surgeons in diagnosing instability-related shoulder lesions on magnetic resonance arthrography? A multicenter reproducibility and accuracy study

BACKGROUND

We compared the diagnostic reproducibility and accuracy of musculoskeletal radiologists with orthopaedic shoulder surgeons in 2 large medical centers in assessing magnetic resonance arthrograms (MRAs) of patients with traumatic anterior shoulder instability.

METHODS

Forty-five surgically confirmed MRAs were assessed by 4 radiologists, 4 orthopaedic surgeons, 2 radiologic teams, and 2 orthopaedic teams. During MRA assessment and surgery, the same 7-lesion scoring form was used. κ Coefficients, sensitivity, specificity, and differences in percentage of agreement or correct diagnosis (P < .05, McNemar test) were calculated per lesion and overall per the 7 lesion types.

RESULTS

The overall κ between the individual radiologists (κ = 0.51, κ = 0.46) and orthopaedic surgeons (κ = 0.46, κ = 0.41) was moderate. Although the overall percentage of agreement between the radiologists was slightly higher than that between the orthopaedic surgeons in both centers (80.0% vs 77.5% and 75.2% vs 73.7%), there was no significant difference. In each medical center, however, the most experienced orthopaedic surgeon was exceedingly more accurate than both radiologists per the 7 lesion types (81.9% vs 72.4%/74.6% and 76.5% vs 67.3%/73.7%). In 3 of 4 cases, this difference was significant. Overall accuracy improvement through consensus assessment was merely established for the weakest member of each team.

CONCLUSION

Experienced orthopaedic surgeons are more accurate than radiologists in assessing traumatic anterior shoulder instability-related lesions on MRA. In case of diagnosis disagreement, these orthopaedic surgeons should base their treatment decision on their own MRA interpretation.

Glenoid notch MRI findings do not predict normal variants of the anterior and superior labrum

AIM

To determine (1) the relationship of a glenoid notch to the presence of a normal labral variant in the anterior-superior glenoid labrum; (2) the inter- and intra-observer reliability of recognising a glenoid notch; and (3) whether magnetic resonance arthrography (MRA) is more reliable than non-contrast magnetic resonance imaging (MRI) in visualising a glenoid notch.

MATERIALS AND METHODS

From 1995 through 2010, 104 patients underwent MRI or MRA before diagnostic shoulder arthroscopy by the senior author. Five blinded musculoskeletal radiologists independently read the images twice to evaluate for the presence or absence of a glenoid notch. Fifty-nine (57%) patients had normal anterior-superior labral variants. The authors calculated the relationship of the readings to the arthroscopically determined presence or absence of a normal labral variant and the reading's diagnostic performance and rater reliability.

RESULTS

On average, 38% (range 9-65%) of the glenoid scans were read as notched. The sensitivity, specificity, positive predictive value, and negative predictive value of the notch relative to the presence of a normal variant were 43.1%, 71.2%, 70.2%, and 48% versus 44.3%, 77.5%, 79.4%, and 56.1% for MRI and MRA, respectively. The overall average intra-observer κ-values were 0.438 (range 0.203-0.555) and 0.346 (range -0.102 to 0.570) for MRI and MRA, respectively. The average interobserver intra-class correlation coefficient reliability values were 0.730 (range 0.693-0.760) and 0.614 (range 0.566-0.662) for MRI and MRA, respectively.

CONCLUSIONS

A notched glenoid on MRI lacks sufficient diagnostic performance and rater reliability for the clinical detection and prediction of normal anterior-superior labral variants.

Approach to the treatment of primary anterior shoulder dislocation: A review

Glenohumeral joint dislocation is common among younger, active patients. Anterior dislocation is the most common direction of instability following a traumatic event. Due to a high rate of recurrence following primary traumatic anterior shoulder dislocation, an evidence-based approach is necessary to determine the best treatment regime for a patient presenting with this problem. A history, physical examination, and radiographic imaging can help guide treatment recommendations by determining the extent of soft tissue damage following dislocation. Controversies in the treatment of the first-time dislocator include the length and position of immobilization following dislocation, and the role of initial surgical stabilization. This article outlines the treatment options for the first-time glenohumeral dislocator, with an emphasis on the available evidence in the literature. Where applicable, the criteria known as the Strength of Recommendation Taxonomy were used to summarize the strength of evidence available for recommendations.

Does the experience level of the radiologist, assessment in consensus, or the addition of the abduction and external rotation view improve the diagnostic reproducibility and accuracy of MRA of the shoulder?

AIM

To prospectively evaluate the influence of observer experience, consensus assessment, and abduction and external rotation (ABER) view on the diagnostic performance of magnetic resonance arthrography (MRA) in patients with traumatic anterior-shoulder instability (TASI).

MATERIALS AND METHODS

Fifty-eight MRA examinations (of which 51 had additional ABER views) were assessed by six radiologists (R1-R6) and three teams (T1-T3) with different experience levels, using a seven-lesion standardized scoring form. Forty-five out of 58 MRA examination findings were surgically confirmed. Kappa coefficients, sensitivity, specificity, and differences in percent agreement or correct diagnosis (p-value, McNemar's test) were calculated per lesion and overall per seven lesion types to assess diagnostic reproducibility and accuracy.

RESULTS

Overall kappa ranged from poor (k = 0.17) to moderate (k = 0.53), sensitivity from 30.6-63.5%, and specificity from 73.6-89.9%. Overall, the most experienced radiologists (R1-R2) and teams (T2-T3) agreed significantly more than the lesser experienced radiologists (R3-R4: p = 0.014, R5-R6; p = 0.018) and teams (T2-T3: p = 0.007). The most experienced radiologist (R1, R2, R3) and teams (T1, T2) were also consistently more accurate than the lesser experienced radiologists (R4, R5, R6) and team (T3). Significant differences were found between R1-R4 (p = 0.012), R3-R4 (p = 0.03), and T2-T3 (p = 0.014). The overall performance of consensus assessment was systematically higher than individual assessment. Significant differences were established between T1-T2 and radiologists R3-R4 (p<0.001, p = 0.001) and between T2 and R3 (p<0.001/p = 0.001) or R4 (p = 0.050). No overall significant differences were found between the radiologists' assessments with and without ABER.

CONCLUSION

The addition of ABER does not significantly improve overall diagnostic performance. The radiologist's experience level and consensus assessment do contribute to higher reproducibility and accuracy.

Traumatic shoulder injuries: a force mechanism analysis-glenohumeral dislocation and instability

OBJECTIVE

Acute traumatic glenohumeral dislocation is one of the most commonly encountered shoulder injuries and can produce a complex combination of associated bony and soft-tissue injuries, the full extent of which is often initially underappreciated. The objectives of this article are to illustrate the relevant anatomy of the shoulder and provide a more intuitive understanding of the complex biomechanics of traumatic glenohumeral instability through the use of 3D modeling and animation to improve the radiologist's awareness of some of the most common injury patterns, and potentially improve the detection of associated injuries. Emphasis is placed on the most critical injuries to determine the ultimate treatment modality, and imaging recommendations are provided.

CONCLUSION

Understanding the force mechanisms responsible for traumatic glenohumeral dislocation can potentially improve detection of associated secondary injuries, which can guide more effective injury classification and ultimately direct more appropriate and timely intervention.

The importance of CT for the pre-operative surgical planning in recurrent anterior shoulder instability

BACKGROUND

MRI is the current pre-operative imaging standard in recurrent anterior shoulder instability; however, CT has increasingly gained interest due to its advantages in the detection of bony glenoid defects. This study compares the value of CT imaging and MRI for pre-operative surgical planning in recurrent anterior shoulder instability.

METHODS

Between 2006 and 2009, 83 patients presented to the author's department with recurrent anterior shoulder instability. For 48 patients, both, pre-operative MRI and CT images were available. The respective patho-morphological descriptions were retrospectively compared with the intra-operative findings. The effect of each imaging technique on the pre-operative surgical planning was analyzed and the accuracy in predicting the necessity of open versus arthroscopic surgery was compared.

RESULTS

In determining the necessity of open versus arthroscopic surgery CT imaging rendered an inaccurate prediction in 4.8 % of the cases which is less than the 25.0 % calculated for MRI. (p = 0.019). MRI showed a low sensitivity (35.3 %) in the detection of significant glenoid bone defects (≥20 % of the glenoid width measured on en-face views using a best-fit circle technique) while CT imaging provided an accurate prediction of the intra-operative finding in all cases.

CONCLUSION

Despite the advantages of MRI in the detection of soft tissue damages in recurrent anterior shoulder instability CT imaging proved to be more important for pre-operative planning by prevailing in the detection of glenoid defects. Therefore, the replacement of MRI as preoperative imaging standard with CT imaging is recommended.

Glenoid bone loss: assessment with MR imaging

PURPOSE

To investigate the agreement among magnetic resonance (MR) imaging, computed tomography (CT), and arthroscopy in the measurement of glenoid bone loss.

MATERIALS AND METHODS

This study was approved by the institutional ethics committee. One hundred seventy-six patients (158 male and 18 female patients; mean age, 26.8 years ± 12.3) with anterior shoulder dislocation underwent both shoulder MR imaging and CT examination. Anterior straight line length, glenoid width, and best-fit bone loss were measured with MR imaging and CT. Sixty-five patients also underwent arthroscopy, which was used as the standard of reference. Assessment of glenoid bone loss at MR imaging was compared with that at CT and arthroscopy. Inter- and intrareader reproducibility of MR imaging-derived measurements of glenoid bone loss was evaluated.

RESULTS

There was excellent correlation between CT and MR imaging with regard to anterior straight line length (r = 0.97, P < .0001), glenoid width (r = 0.95, P < .0001), and severity of glenoid bone loss-particularly with use of best-fit circle width (r = 0.83, P < .0001) rather than best-fit circle area (r = 0.82, P < .0001). In the assessment of glenoid bone loss, the correlation between CT and arthroscopy (r = 0.91, P < .0001) was marginally better than that between MR imaging and arthroscopy (r = 0.84, P < .0001). The inter- and intrareader correlations of MR imaging-derived measurements of glenoid bone loss were excellent (R = 0.90-0.95).

CONCLUSION

MR imaging assessment of glenoid bone loss, particularly with use of glenoid width, is almost as accurate as CT assessment.

Evaluation and management of posterior shoulder instability

CONTEXT

Posterior shoulder instability is a commonly misdiagnosed disorder in many competitive athletes.

TYPE OF STUDY

Clinical review.

EVIDENCE ACQUISITION

Relevant studies on posterior shoulder instability from 1950 to 2010 in PubMed and Cochrane databases were reviewed.

RESULTS

A total of 107 studies were reviewed.

CONCLUSION

Patients who have undergone at least 6 months of physical therapy and still experience instability symptoms should be considered for surgical stabilization directed at their underlying pathology.

Dual-window subscapularis-sparing approach: a new surgical technique for combined reconstruction of a glenoid bone defect or bankart lesion associated with a HAGL lesion in anterior shoulder instability

Combined bankart lesion and humeral avulsion of glenohumeral ligament lesion (HAGL) is a well-described pathologic complex in anterior shoulder instability; open surgical approaches with and without arthroscopic assistance have been suggested for simultaneous 1-stage repair of these lesions. Presence of a significant glenoid bone defect (inverted-pear glenoid) adds to the complexity of the problem and necessitates a bony reconstruction procedure. Open surgical approaches described for management of this combined lesion complex in anterior shoulder instability necessitate a subscapularis-cutting approach; suboptimal healing of the tenotomized subscapularis and subsequent delayed rehabilitation predisposes to late subscapularis dysfunction, and this compromises clinical outcomes. This study describes a new surgical technique that utilizes a dual-window approach through the subscapularis muscle; the dual window enables access to the glenoid and humeral lesions without the need for a subscapularis tenotomy. The approach can be used to perform a congruent-arc Latarjet procedure (for glenoid bone defects) or a Bankart repair (for capsulolabral lesions), in combination with a HAGL repair. Preliminary arthroscopy is essential to identify significant bone defects and HAGL lesions. The dual-window approach for reconstruction of the lesions involves (1) a lateral "subscapularis-sparing" window to identify and repair the HAGL lesion; (2) a medial "subscapularis muscle-splitting" window to perform either a glenoid capsulolabral reconstruction or a congruent-arc Latarjet procedure; and (3) a balanced inferior capsular shift and lateralization procedure of the glenohumeral capsule. Technical tips and guidelines to avoid complications are discussed, and a rehabilitation protocol is presented.

Glenohumeral joint instability

Due to the configuration of its bony elements, the glenohumeral joint is the most mobile joint of the body, but also an inherently unstable articulation. Stabilization of the joint is linked to a complex balance between static and dynamic soft tissue stabilizers. Because of complex biomechanics, and the existence of numerous classifications and acronyms to describe shoulder instability lesions, this remains a daunting topic for most radiologists. In this article we provide a brief review of the anatomy of the glenohumeral joint, as well as the classifications and the pathogenesis of shoulder instability. Technical aspects related to the available imaging techniques (including computed tomography [CT] arthrography, magnetic resonance imaging [MRI], and MR arthrography) are reviewed. We then describe the imaging findings related to shoulder instability, focusing on those elements that are important to the clinician.

Evaluation of glenohumeral instability

Glenohumeral instability is a common cause of shoulder disability. A wide spectrum of causes and presentations can make diagnosing subtle instability very difficult. This article describes clinical evaluation of the glenohumeral joint using pertinent components of the patient history, physical examination, and selective imaging to arrive at the diagnosis of glenohumeral instability in the symptomatic patient.

MR imaging in congenital and acquired disorders of the pediatric upper extremity

Various congenital and acquired disorders can affect the upper extremity in pediatric and adolescent patients. MR imaging can provide unique anatomic and diagnostic information in the evaluation of many of these disorders, including inflammatory, infectious, neoplastic, and arthritic conditions. This article rounds out the issue on pediatric musculoskeletal MR imaging. It focuses on the evaluation of more common congenital disorders, and mainly sports-related injuries of the shoulder, elbow, and wrist in children. MR imaging can be more challenging in diagnosis of some of these disorders. Features of overuse injuries in skeletally immature athletes are a unifying theme throughout the article.

Use of the fulcrum axis improves the accuracy of true anteroposterior radiographs of the shoulder

In 100 patients the fulcrum axis which is the line connecting the anterior tip of the coracoid and the posterolateral angle of the acromion, was used to position true anteroposterior radiographs of the shoulder. This method was then compared with the conventional radiological technique in a further 100 patients.

Three orthopaedic surgeons counted the number of images without overlap between the humeral head and glenoid and calculated the amount of the glenoid surface visible in each radiograph. The analysis was repeated for intraobserver reliability. The learning curves of both techniques were studied.

The amount of free visible glenoid space was significantly higher using the fulcrum-axis method (64 vs 31) and the comparable glenoid size increased significantly (8.56 vs 6.47). Thus the accuracy of the anteroposterior radiographs of the shoulder is impaired by using this technique. The intra and interobserver reliability showed a high consistency. No learning curve was observed for either technique.

An analysis of capsular area in patients with anterior, posterior, and multidirectional shoulder instability

BACKGROUND

Although increased capsular volume has been implicated in shoulder instability, there is a paucity of clinical evidence to quantify the size of the capsule with specific instability conditions of the shoulder.

HYPOTHESIS

Shoulder capsular area, as measured by magnetic resonance arthrography, is increased with specific patterns of shoulder instability.

STUDY DESIGN

Cross-sectional study; Level of evidence, 4.

METHODS

During an 8-month period, all patients with a diagnosis of anterior (n = 19), posterior (n = 14), or multidirectional (n = 13) instability of the shoulder and who were assessed with a magnetic resonance arthrogram were reviewed. A group of 10 control patients without clinical instability were also identified. The magnetic resonance arthrograms of all groups were randomly mixed, and 5 reviewers recorded measures of capsular length and area and determined labral abnormalities. The magnetic resonance arthrogram measurements were compared between groups, and interobserver agreement was determined.

RESULTS

The cross-sectional area of the capsule was increased in patients with posterior (P = .017) or multidirectional instability (P = .021) versus controls, but not in patients with anterior instability. Additionally, the posteroinferior cross-sectional area was increased in patients with posterior (P = .001), multidirectional (P = .003), and anterior (P = .008) instability. In patients with a posterior labral tear, the mean axial (P = .043) and mean posteroinferior sagittal cross-sectional area (P = .011) was increased, but there were no differences in cross-sectional area for those with an anterior labral tear. The overall interobserver reliability was very good (correlation coefficient range, 0.68-0.94).

CONCLUSION

Our results reinforce the concept that capsular elongation and laxity, either preexisting or acquired, play a role in certain instability conditions of the shoulder. Additional work is needed to determine how to correlate surgical decision making with the cross-sectional area measurements demonstrated in this study.

Quantification of a glenoid defect with three-dimensional computed tomography and magnetic resonance imaging: a cadaveric study

Bone loss of the glenoid is a common finding in anterior glenohumeral instability. Several methods to measure the size of a glenoid defect have been described but have not been validated. In this study, 14 cadaver glenoids with a randomly created anteroinferior glenoid defect were used for validation of the so-called circle method. Measurements were done by 2 researchers on digital photographs, 3-dimensional (3D) computed tomography (CT) scans, and magnetic resonance images (MRI). The correlation coefficient (r(2)) for comparing measurements from the digital photographs with the CT scans was 0.97 for researcher 1 and 0.90 for researcher 2. When they compared digital images with MRI, the r(2) was 0.93 for researcher 1 and 0.92 for researcher 2. No statistical differences were found between the 2 researchers. The circle method is a simple method for preoperative quantification of a glenoid defect. Measurements can be done with 3D CT scans as well as MRI.

MR arthrography of traumatic anterior shoulder lesions showed modest reproducibility and accuracy when evaluated under clinical circumstances

INTRODUCTION

We examined the reproducibility and accuracy of high-field MRA in traumatic anterior shoulder instability under conditions resembling clinical practice and assessed the influence of observer experience.

MATERIALS AND METHODS

Two radiologists with different experience levels evaluated 61 MRAs. Assessment was independent, blinded and non-sequential. For 40 MRAs, surgical reports were available to assess diagnosis accuracy and influence of observer experience. The assessed lesions were cuff lesions, Hill-Sachs lesions, bony and classic Bankart lesions, greater humeral tuberosity fractures, SLAP lesions and joint capsule lesions. Reproducibility was quantified using kappa coefficients. Accuracy was evaluated with sensitivity and specificity rates, positive and negative predictive values. Differences in the percentage of correctly diagnosed MRAs between the radiologists were tested using McNemar's test for paired proportions.

RESULTS

Inter-observer k-values ranged from 0.03 for joint capsule lesions to 0.45 for humeral head lesions. The overall kappa was 0.21 (95% CI; 0.12-0.30). We also observed markedly lower sensitivity and specificity rates than those reported in the literature for most lesions. The more experienced radiologist correctly diagnosed 78.9% of all lesions compared to 65.4% for the less experienced radiologist (P < 0.001; McNemar's test).

CONCLUSION

MRA-interpretations of traumatic anterior shoulder instability should be regarded with caution in clinical practice. The experience level of radiologists can affect reproducibility and accuracy.

Imaging of sports injuries of the upper extremity in children

Competitive athletics in school-aged children has become the norm rather than the exception. The increased repetitive stresses placed on the upper extremity in a wide variety of sports result in a host of injuries unique to the skeletally immature athlete. This article focuses on a discussion of the more common upper extremity injuries encountered in the child athlete and the role of radiography and MRI in diagnosis and management.

MR Imaging of the Glenohumeral Ligaments

The glenohumeral ligaments, particularly the inferior one, are the major passive stabilizers of the joint, and the labrum functions as a site of ligamentous attachment. The strong union between the collagen fibers of the glenohumeral ligaments and the glenoid labrum is more resistant to injury than the union between the glenoid rim and the labrum. Labral tears associated with glenohumeral instability are therefore usually secondary to avulsion rather than impaction. This article reviews the normal MR imaging anatomy, variants and pitfalls of the glenohumeral ligaments, and the basic biomechanics of the glenohumeral ligaments. Examples of injuries involving these structures are provided.

MR imaging in sports-related glenohumeral instability

Sports-related shoulder pain and injuries represent a common problem. In this context, glenohumeral instability is currently believed to play a central role either as a recognized or as an unrecognized condition. Shoulder instabilities can roughly be divided into traumatic, atraumatic, and microtraumatic glenohumeral instabilities. In athletes, atraumatic and microtraumatic instabilities can lead to secondary impingement syndromes and chronic damage to intraarticular structures. Magnetic resonance (MR) arthrography is superior to conventional MR imaging in the diagnosis of labro-ligamentous injuries, intrinsic impingement, and SLAP (superior labral anteroposterior) lesions, and thus represents the most informative imaging modality in the overall assessment of glenohumeral instability. This article reviews the imaging criteria for the detection and classification of instability-related injuries in athletes with special emphasis on the influence of MR findings on therapeutic decisions.

A systematic approach to magnetic resonance imaging interpretation of sports medicine injuries of the shoulder

Magnetic resonance imaging has developed as a useful imaging modality in the evaluation of the athlete with shoulder pain. The multiplanar capabilities of magnetic resonance imaging make it ideal for detecting the anatomical variations of the osseous outlet that may contribute to the clinical syndrome of impingement. Its superb soft tissue contrast and spatial resolution allow for accurate differentiation between tendinopathy, partial-thickness tear, and full-thickness tear of the rotator cuff and also allow for detection of the subtle lesions of the capsule and labrum that are associated with shoulder instability. However, to accurately interpret the numerous images and pulse sequences obtained in a standard magnetic resonance examination of the shoulder, it is helpful to have a systematic approach to ensure that each of the pertinent anatomical structures are evaluated. This article will provide a systematic approach to the interpretation of a magnetic resonance examination of the shoulder. The normal imaging appearance of each anatomical structure will be described, and the most useful pulse sequences and imaging planes for the evaluation of each structure will be discussed. Finally, the signs of injury will be described and illustrated.

Recurrent posterior shoulder instability

Recurrent posterior shoulder instability is an uncommon, debilitating condition in young adults that is being diagnosed with increasing frequency. Although a number of predisposing factors have been identified, their relative importance remains poorly understood. Poor results have been reported following operative intervention to treat recurrent posterior instability with nonanatomic techniques. The more recent development of lesion-specific surgery has improved clinical results, particularly when that surgery has been performed arthroscopically. Operative treatment is therefore being increasingly recommended at an earlier stage to patients who do not respond to supervised rehabilitation programs.

Glenohumeral instability and dislocation

Glenohumeral joint instability and dislocations are common diagnoses seen by physicians. There are many different pathologic etiologies for these conditions. A thorough understanding of the history,physical examination, pathoanatomy, and classification systems is required to make an accurate diagnosis. With the appropriate diagnosis, the clinician can choose the correct treatment and improve the patient's outcome.

Postoperative shoulder rehabilitation

This article focuses on the rehabilitation considerations for several shoulder surgeries: acromioplasty, rotator cuff repair, rotator cuff debridement, Bankart repair, thermal capsulorrhaphy, superior labral anterior posterior repair, multidirectional instability, proximal humerus fracture, surgical management of the stiff shoulder, arthroplasty,and fusion. General guidelines are presented for discussing and planning rehabilitation for patients, including exercises, timing of progression, patient education, precautions or restrictions, and expectations.

Anterior shoulder dislocation: quantification of glenoid bone loss with CT

OBJECTIVE

In recurrent anterior shoulder dislocation, glenoid bone loss may predispose the patient to further dislocation and failure of a Bankart repair. This study investigates the quantification of glenoid bone loss in anterior shoulder dislocation using CT.

SUBJECTS AND METHODS

CT examinations were performed on 40 patients (average age, 31 years; range, 13-82 years), comprising 46 shoulders with anterior dislocation and 34 contralateral normal shoulders. Twenty shoulders in 10 healthy subjects were also examined. Both shoulders were examined simultaneously. Image reconstruction included oblique sagittal reformatted images en face to the glenoid fossa. Seven aspects of glenoid fossa shape and size were measured, including the cross-sectional area, maximum width, maximum height, and flattening of the anterior glenoid curvature.

RESULTS

Variable flattening of the anterior glenoid curvature was a feature in 42 (91%) of 46 dislocated shoulders although it was seen in only two (4%) of 54 normal shoulders. Anterior glenoid flattening increased exponentially with an increasing number of dislocations. Anterior glenoid flattening, decreased maximum glenoid width, and decreased maximum width-to-length ratio were the most useful measures of bone loss. Maximum glenoid width was smaller than on the contralateral side in 79% of patients with unilateral dislocation by an average of 3.0 mm (range, 0.1-10 mm) or 10.8% (range, 0.4-32%). Glenoid cross-sectional area was a less useful measure of glenoid bone loss.

CONCLUSION

Flattening of the anterior glenoid curvature is shown in most patients with anterior dislocation. In unilateral dislocation, a comparison of maximum glenoid width with that on the contralateral side was the best discriminator of moderate to severe glenoid bone loss.

Sports-related injuries of the shoulder: instability

With current technology a properly conceived imaging strategy can demonstrate instability lesions in the athlete. Plain radiographs can diagnose acute dislocations and assess successful reductions. In addition, plain radiographs can demonstrate Hill-Sachs and, more importantly for instability, osseous Bankart lesions. In the acute setting, conventional MRI nicely demonstrates labral Bankart, ligamentous. and tendonous injuries that result from dislocations and can lead to instability. In the setting of chronic instability, MR arthrography best evaluates these lesions. In the postoperative shoulder, muitislice CT arthrography may be the modality of choice, but further investigation is needed. If large series validate multislice CT arthrography for the evaluation of postoperative instability lesions, this technique may become widely used in athletes and in other populations where recurrent instability is a problem. Other imaging strategies may also find an increasing central role in evaluating shoulder instability lesions. Indirect MR arthrography, for example, may have a role in assessing these lesions in athletes . Another intriguing technology for this application is the development of high field (0.5 Tesla or greater) open magnets. In such a setting, physiological relationships in the shoulder with motion and stress may be evaluated. Such imaging may farther illuminate our understanding of the stable and unstable shoulder. Unfortunately, with all imaging modalities, whether widely used or experimental, outcomes data is Lacking. How do the various imaging modalities and strategies affect patient outcome? The answer is unknown and needs to be answered before a definitive patient work-up for shoulder instability can be established.