MR arthrography of the labral capsular ligamentous complex in the shoulder: imaging variations and pitfalls

Prevalence of the anterosuperior capsulolabral anatomical variations and their association with pathologies of the glenoid labrum: a systematic review and meta-analysis

PURPOSE

Differentiating the anatomical variations of the anterosuperior portion of the glenoid labrum from pathologies is important to avoid unnecessary iatrogenic complications resulting from inaccurate diagnosis. Additionally, the presence of several variations was reported to be conductive to lesions involving the glenoid labrum. Thus, the aim of this study was to state the prevalence rates of the sublabral recess, sublabral foramen, and the Buford complex, and to verify their association with labral lesions.

METHODS

Systematic search of electronic databases was conducted to gain potentially eligible literature. Suitable studies were selected in a two-round screening, and relevant data were subsequently extracted. Calculation of the pooled prevalence estimates, including sub-analyses on cohort size, study type, and geographical variance, was conducted. Pooled analysis of risk ratios (RR) was used to assess the conductive nature of the discussed variants to superior labrum anterior to posterior (SLAP) lesions.

RESULTS

The screening resulted in selection of 20 studies investigating the morphological features of the glenoid labrum, consisting of 7601 upper limbs. On the bases of random-effects meta-analysis the sublabral recess, sublabral foramen and Buford complex occur with a pooled prevalence of 57.2% (95% CI 30.0-84.4%), 13.5% (95% CI 8.2-18.9%), and 3.0% (95% CI 1.5-4.5), respectively. Moreover, individuals with Buford complex have RR 2.4 (95% CI 1.3-4.7) of developing SLAP lesions, especially type II (95.5%; 95% CI 86.1-100%), whereas such risk for sublabral recess and sublabral foramen was not statistically significant.

CONCLUSION

Morphological variants of the glenoid labrum posing diagnostic confusion are frequently observed. Gradually, the Buford complex may be a predisposing factor for sustaining a SLAP lesion.

Association Between Medial Displacement of the Middle Glenohumeral Ligament and Subscapularis Tear Severity

Background:

The intraoperative invisible middle glenohumeral ligament (MGHL) test has been shown to be associated with a subscapularis tendon retraction. However, the preoperative location of the MGHL and its association with subscapularis tear severity has not been evaluated.

Purpose:

To determine (1) the interrater reliability for identification and position of the MGHL, (2) any association between the MGHL position and subscapularis tears, and (3) the cutoff point at which MGHL position can predict subscapularis tear severity.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

The magnetic resonance imaging (MRI) scans and surgical records of 176 patients were retrospectively reviewed by 3 independent orthopaedists. MGHL's identification, level (its position on axial MRI), and medial retraction ratio (distance from the lesser tuberosity to the MGHL divided by the width of the glenoid) were documented, and the interobserver agreement of the 3 indices was assessed. We calculated the association between subscapularis tears and the MGHL level and medial retraction ratio. Receiver operating characteristic (ROC) curve analyses were conducted to establish the optimal threshold of the MGHL medial retraction ratio to predict subscapularis tear.

Results:

The MGHL was identified by at least 2 reviewers in 124 individuals (70.5%). The interobserver reliability was very good for MGHL identification (κ = 0.766), moderate for MGHL level (κ = 0.582), and excellent for MGHL medial retraction ratio (intraclass correlation coefficient = 0.848). A low, positive correlation between MGHL level and subscapularis tear severity was found (Somers d = 0.392, P < .001), as well as a significant association between the medial retraction ratio and Lafosse classification of subscapularis tear size ( P < .001). A medial retraction ratio of ≥1.25 had a sensitivity of 0.70, a specificity of 0.83, and a positive likelihood ratio of 4.20, with excellent accuracy (area under the ROC curve = 0.820) to predict severe subscapularis tear.

Conclusion:

The MGHL was identified in 70.5% of shoulder MRIs. The location of the MGHL on preoperative MRI, as described by its level and the medial retraction ratio, was significantly associated with subscapularis tear severity, and a medial retraction ratio of ≥1.25 was predictive of a severe subscapularis tear.

Comparison of Perioperative Complications Following Surgical Treatment of Shoulder Instability

Background

Surgical repair for shoulder instability includes arthroscopic Bankart, open Bankart, and Latarjet-Bristow.

Methods

This is a cohort study of patients who underwent arthroscopic Bankart, open Bankart, or Latarjet-Bristow procedures that were identified within the National Surgical Quality Improvement Program database (2007-2019). Unadjusted and adjusted analyses were performed (α = 0.05). Outcomes included 30-day adverse events, readmission, and operative time.

Results

This study included 10,955 patients (9128 arthroscopic Bankart, 1148 open Bankart, and 679 Latarjet-Bristow). Compared with arthroscopic Bankart, Latarjet-Bristow had longer operative times (129.96 [95% CI: 126.49-133.43] vs. 86.35 [85.51-87.19] minutes), along with a higher percentage of serious adverse events (2.5% vs. 0.4%), reoperation (1.9% vs. 0.1%), readmission (1.8% vs. 0.3%), thromboembolic complications (0.4% vs. 0.1%), and sepsis (0.4% vs. 0.0%) (P < .05 for all). Open Bankart had longer operative times (98.17 [95.52-100.82] vs. 86.35 [85.51-87.19] minutes) and a higher percentage of sepsis (0.2% vs. 0.0%) (P < .05 both). Latarjet-Bristow had increased odds of a serious adverse event (odds ratio [OR]: 7.68 [4.19-14.07]), reoperation (OR: 17.32 [7.58-39.56]), readmission (OR: 5.73 [2.84-11.54]), and deep wound complications (OR: 14.98 [3.92-57.23]) (P < .05 for all). In comparing the relative utilization of arthroscopic versus open Bankart, arthroscopic Bankart increased (83.4% to 91.2%) while open Bankart decreased (16.6% to 8.8%) from the 2011-2013 time period to 2017-2019 (P_trend < .001).

Conclusion

In addition to a low complication rate, the relative utilization of arthroscopic Bankart increased compared with open Bankart over the past decade. Furthermore, Latarjet-Bristow was associated with a higher incidence of serious adverse events than arthroscopic Bankart.

The Cartilage Wear Index: A new evaluation method to improve patient selection in surgical treatment of recurrent posterior glenohumeral instability

Background

The purpose of this study was 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

Twenty-six 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 (CWI). Two subgroups were analyzed with regard to the preoperative CWI and shoulder outcome scores: Single Assessment Numerical Evaluation (SANE) and Western Ontario Shoulder Instability Index (WOSI).

Results

The median age at operation was 28 (interquartile range = 21-33) years. Median overall postoperative outcome assessment demonstrated a SANE of 90 and a WOSI of 385. The median CWI was 1.02. Subgroup analysis revealed worse median WOSI and SANE scores in patients with a CWI >1.02 and a strong correlation between a high preoperative CWI and a higher postoperative WOSI score (R = 0.58; P = .038).

Conclusion

The CWI can be useful to identify patients who might obtain better outcomes when treated with arthroscopic labral repair in posterior shoulder instability.

Posterior shoulder labrocapsular structures in all aspects; 3D volumetric MR arthrography study

Pathologies of the posterior labrocapsular structures of the shoulder joint are far less common than anterior labrocapsuloligamentous lesions. Most of these pathologies have been associated with traumatic posterior dislocation. A smaller portion of the lesions include posterior extension of superior labral anteroposterior lesions, posterior superior internal impingement, and damage to the posterior band of the inferior glenohumeral ligament. Labrocapsular anatomic variations of the posterior shoulder joint can mimic labral pathology on conventional MR and occasionally on MR arthrographic images. Knowledge of this variant anatomy is key to interpreting MR images and studying MR arthrography of the posterior labrocapsular structure to avoid misdiagnosis and unnecessary surgical procedures. In this article, we review normal and variant anatomy of the posterior labrocapsular structure of the shoulder joint based on MR arthrography and discuss how to discriminate normal anatomic variants from labrocapsular damage.

Comparison of MRI and MRA for the diagnosis of rotator cuff tears: A meta-analysis

BACKGROUND

Numerous quantitatively based studies measuring the accuracy of MRI and MRA for the diagnosis of rotator cuff tears remain inconclusive. In order to compare the accuracy of MRI with MRA in detection of rotator cuff tears a meta-analysis was performed systematically.

METHODS

PubMed/Medline and Embase were utilized to retrieve articles comparing the diagnostic performance of MRI and MRA for use in detecting rotator cuff tears. After screening and diluting out the articles that met inclusion criteria to be used for statistical analysis the pooled evaluation indexes including sensitivity and specificity as well as hierarchical summary receiver operating characteristic (HSROC) curves with 95% confidence interval (CI) were calculated.

RESULTS

Screening determined that 12 studies involving a total of 1030 patients and 1032 shoulders were deemed viable for inclusion in the meta-analysis. The results of the analysis showed that MRA has a higher sensitivity and specificity than MRI for the detection of any tear; similar results were observed in the detection of full-thickness tears. However, for the detection of partial-thickness tear, MRI has similar performance with MRA.

CONCLUSION

MRI is recommended to be a first-choice imaging modality for the detection of rotator cuff tears. Although MRA have a higher sensitivity and specificity, it cannot replace MRI after the comprehensive consideration of accuracy and practicality.

Detecting Rotator Cuff Tears: A Network Meta-analysis of 144 Diagnostic Studies

BACKGROUND

Many imaging techniques have been developed for the detection of rotator cuff tears (RCTs). Despite numerous quantitative diagnostic studies, their relative accuracy remains inconclusive.

PURPOSE

To determine which of 3 commonly used imaging modalities is optimal for the diagnosis of RCTs.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

Studies evaluating the performance of magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA), and ultrasound (US) used in the detection of RCTs were retrieved from the PubMed/MEDLINE and Embase databases. Diagnostic data were extracted from articles that met the inclusion/exclusion criteria. A network meta-analysis was performed using an arm-based model to pool the absolute sensitivity and specificity, relative sensitivity and specificity, and diagnostic odds ratio as well as the superiority index for ranking the probability of these techniques.

RESULTS

A total of 144 studies involving 14,059 patients (14,212 shoulders) were included in this network meta-analysis. For the detection of full-thickness (FT) tears, partial-thickness (PT) tears, or any tear, MRA had the highest sensitivity, specificity, and superiority index. For the detection of any tear, MRI had better performance than US (sensitivity: 0.84 vs 0.81, specificity: 0.86 vs 0.82, and superiority index: 0.98 vs 0.22, respectively). With regard to FT tears, MRI had a higher sensitivity and superiority index than US (0.91 vs 0.87 and 0.67 vs 0.28, respectively) and a similar specificity (0.88 vs 0.88, respectively). The results for PT tears were similar to the detection of FT tears. A sensitivity analysis was performed by removing studies involving only 1 arm for FT tears, PT tears, or any tear, and the results remained stable.

CONCLUSION

This network meta-analysis of diagnostic tests revealed that high-field MRA had the highest diagnostic value for detecting any tear, followed by low-field MRA, high-field MRI, high-frequency US, low-field MRI, and low-frequency US. These findings can help guide clinicians in deciding on the appropriate imaging modality.

Sonoarthrographic examination of posterior labrocapsular structures of the shoulder joint

OBJECTIVE

To describe the posterior labral lesions and labrocapsular abnormalities of the shoulder on sonoarthrography and to compare these findings with MR arthrography results.

METHODS

82 shoulders were initially evaluated with ultrasonography and MRI and then were examined with sonoarthrography and MR arthrography following intraarticular injection of diluted gadolinium solution. The ultrasonography images were prospectively evaluated for the presence of posterior labral tear, sublabral cleft, and posterior capsular abnormalities by two radiologists. The diagnostic accuracy of sonoarthrography in the detection of posterior labral tears and posterior labrocapsular variants was compared with that of MR arthrography.

RESULTS

In sonoarthrographic examinations of 82 shoulders, 5 and 6 posterior labral tears were identified by Observer 1 and 2, respectively. Moreover, 6 and 7 posterior sublabral clefts, and 2 and 3 posterior synovial folds were identified by Observer 1 and 2, respectively. All the 82 patients were examined with MR arthrography; however, only 14 patients underwent arthroscopic examination. No significant difference was found among the 82 patients with regard to age, gender, and the prevalence of posterior labral tear, posterior labral cleft, and posterior synovial fold (p > 0.05). Interobserver variability showed substantial agreement between the sonoarthrographic and MR arthrographic results of the posterior labrocapsular structures (κ = 0.71, p < 0.05).

CONCLUSION

Posterior labral tears and posterior synovial folds of the shoulder joint can be evaluated non-invasively by sonoarthrography.

ADVANCES IN KNOWLEDGE

Variations and pathologies of posterior labrocapsular structures of the glenohumeral joint are relatively uncommon.Direct (MR) arthrography is the gold-standard imaging modality to evaluate of posterior labrocapsular abnormalities of the glenohumeral joint.Sonoarthrography of the glenohumeral joint may be utilized in clinical practice in patients with contraindications to (MRI).

Diagnostic accuracy of MRA and MRI for the bursal-sided partial-thickness rotator cuff tears: a meta-analysis

BACKGROUND

Numerous quantitatively studies have focused on the diagnosis of bursal-sided partial-thickness rotator cuff tears (RCTs); however, the accuracy of magnetic resonance imaging (MRI) and MR arthrography (MRA) remains inconclusive. This study was performed systematically to compare the diagnostic value of MRA and MRI for the bursal-sided partial-thickness RCTs.

METHODS

Three electronic databases, PubMed, Embase, and Cochrane Library, were utilized to retrieve articles comparing the diagnostic value of MRA and MRI for detecting bursal-sided partial-thickness RCTs. After screening and diluting out the articles that met the inclusion criteria to be used for statistical analysis, the pooled evaluation indexes include sensitivity, specificity, positive and negative predictive values, diagnostic odds ratio (DOR), and the area under the receiver operating characteristic curve (AUC).

RESULTS

Twelve studies involving 1740 patients and 1741 shoulders were identified. The pooled sensitivity, specificity, DOR, and AUC of MRA to diagnose bursal-sided partial-thickness RCTs were 0.77 (95% CI, 0.67-0.85), 0.98 (95% CI, 0.95-0.99), 73.01 (95% CI, 35.01-152.26), and 0.88 (95% CI, 0.85-0.91), respectively. The pooled sensitivity, specificity, DOR, and AUC of MRI were 0.77 (95% CI, 0.66-0.86) and 0.96 (95% CI, 0.81-0.99), and 37.12 (95% CI, 8.08-170.64) and 0.82 (95% CI, 0.78-0.85), respectively.

CONCLUSIONS

This meta-analysis reveals that MRA and MRI have similar diagnostic value for the diagnosis of bursal-sided partial-thickness rotator cuff tears.

MR Imaging of the Upper Limb: Pitfalls, Tricks, and Tips

MR imaging is the modality of choice to evaluate musculoskeletal pathologies of the upper limb in most settings. However, due to the complexity in anatomy, MR imaging can give a false pathologic appearance and lead to several errors in the interpretation of MR imaging findings. Also, several artifacts can be confused with pathologic entities. This article reviews the most frequently encountered conditions in shoulder, elbow, and wrist MR imaging that can represent diagnostic pitfalls mimicking true pathology, together with some possible tips and tricks that can be useful to solve these equivocal cases and achieve a correct diagnosis.

MR arthrographic characterization of posterior capsular folds in shoulder joints

METHODS:

This was a retrospective study of 604 consecutive shoulder MR images and MR arthrograms obtained from April 2010 to January 2018. Extension in the vertical-oblique plan of the posterior synovial fold on MR arthrography was identified according to the posterosuperior, posteroinferior, superoposterior, and inferoposterior portions. The morphologies of the posterior synovial folds on MR arthrography were divided three subtypes. Morphologic appearances of the posterior labrocapsular complex on conventional MR images were described with four subtypes.

RESULTS:

A posterior synovial fold in the shoulder joint was identified in 35 of 604 (5.8%) MR arthrography patients. 8 of 35 posterior synovial fold identified on MR arthrography were confirmed at arthroscopy. The most common MR arthrographic type of the posterior synovial fold was triangular-this was detected in 17 of 35 (48.6%) patients. The most common MRI morphology of the posterior labrocapsular complex was doubled posterior labrum. This was detected in 15 of 35 (42.9%) patients. 17 % of patients with posterior synovial folds who were diagnosed with MR arthrography had normal MRI features. The most common localization of the posterior synovial fold was posterosuperior and posteroinferior portions of the posterior labrocapsular structures. The mean of the shortest distance between the posterior synovial fold and the posterior labrum was significantly higher in the positive arthroscopic synovial fold group than in the negative arthroscopic synovial fold group (p = 0.047).

CONCLUSION:

Posterior synovial folds, normal capsular anatomic variants, are seen rarely on MR arthrography, and tend to be in the posterosuperior and posteroinferior portions of the posterior capsule. Some types of the posterior synovial fold can mimic a posterior labral tear in conventional MRI.

ADVANCES IN KNOWLEDGE:

On a direct MR arthrographic image, a posterior capsular synovial fold may be a normal anatomic variant. A fold is more commonly occur in the posterosuperior and posteroinferior capsular portions. The results of our study may allow differentiation of normal variations from abnormalities in patients with symptomatic shoulder joint.

MR arthrogram of the postoperative glenoid labrum: normal postoperative appearance versus recurrent tears

OBJECTIVE

The purpose of this study is to describe the MR arthrogram appearance of the postoperative glenoid labrum and to describe the features consistent with recurrent tear.

MATERIALS AND METHODS

We identified 30 patients who had undergone glenoid labral repair, had a subsequent MR arthrogram of his or her shoulder, and went on to repeat shoulder arthroscopy. Each MR arthrogram was reviewed blindly, and the glenoid labrum was described as normal, irregular, or torn. Additional findings recorded included the presence or absence of a paralabral cyst and suture anchors in the glenoid. The operative report was also reviewed for each patient to determine the status of the labrum at arthroscopy.

RESULTS

Following consensus review, 18/30 MRIs were felt to demonstrate recurrent glenoid labral tear, 11/30 showed an irregular labrum, and 1/30 was called normal. The radiology impression regarding the presence or absence of a recurrent glenoid labral tear agreed with the operative report in 24/30 (80%) cases, and was discrepant in six. This equals 83.3% sensitivity and 81.8% specificity of MR arthrogram in the diagnosis of recurrent labral tear in this study. A paralabral cyst was present in 3/30 (10%) cases, all three of which were torn.

CONCLUSIONS

MR arthrogram findings of signal equal to gadolinium or fluid within or underlying the glenoid labrum and markedly diminutive or absent labrum were the most useful features to diagnose recurrent tear. Some signal underlying the labrum, which is confined to the anterosuperior quadrant, may be normal. The secondary finding of a paralabral cyst was also highly sensitive for recurrent tear.

Distinct Proximal Humeral Geometry in Chinese Population and Clinical Relevance

BACKGROUND

Replicating humeral anatomy during shoulder arthroplasty is important for good patient outcomes. The proximal humeral geometry of the Chinese population has been rarely reported. We analyzed the geometry of the proximal part of the humerus in Chinese subjects and compared it with that of Western populations and the dimensions of available prostheses.

METHODS

Eighty healthy Chinese subjects underwent computed tomography (CT)-arthrography. Three-dimensional (3D) digital humeral and glenoid models were reconstructed, and geometric parameters were measured. Humeral measurements included the radius of curvature, articular surface diameter and thickness, anterior-posterior/superior-inferior (AP/SI) articular surface diameter ratio, articular surface thickness/radius of curvature ratio, surface arc, inclination angle, retroversion angle, and medial and posterior offsets. Glenoid measurements included SI length, AP length, SI radius, and AP radius.

RESULTS

The average radius of curvature (and standard deviation) of the humeral head was 22.1 ± 1.9 mm, the articular surface diameter averaged 42.9 ± 3.6 mm, and the articular surface thickness averaged 16.9 ± 1.5 mm. There was strong linear correlation between the articular surface diameter and thickness (r = 0.696, p = 0.001), with a linear regression relationship of thickness = 0.357 × diameter + 1.615. The AP/SI articular surface diameter ratio averaged 0.93 ± 0.03; the articular surface thickness/radius of curvature ratio, 0.77 ± 0.05; the surface arc, 153° ± 5.6°; the inclination angle, 133° ± 3.1°; and the retroversion angle, 22.6° ± 10.2°. The medial and posterior offsets averaged 6.3 ± 0.9 mm and 0.4 ± 0.78 mm, respectively; the SI and AP lengths, 30.15 ± 3.70 mm and 20.35 ± 2.56 mm; and the SI and AP radii, 23.49 ± 2.48 mm and 25.54 ± 3.07 mm. Compared with the Western population, the Chinese cohort had a smaller radius of curvature (p < 0.001), smaller articular surface diameter (p = 0.009), larger articular surface thickness/radius of curvature ratio (p < 0.001), larger surface arc (p < 0.001), smaller inclination angle (p < 0.001), and smaller posterior offset (p < 0.001). Unlike the Western population, the Chinese population had higher glenohumeral conformity in the coronal plane than in the axial plane. Many manufacturers' shoulder prostheses do not adequately cover the range of humeral head dimensions in our Chinese cohort.

CONCLUSIONS

The geometric parameters of the humeri in the Chinese population differ from those in other populations. These differences have clinical relevance with regard to implant design and arthroplasty technique and likely affect clinical outcomes.

What can the Radiologist do to Help the Surgeon Manage Shoulder Instability?

Imaging of the shoulder forms an important adjunct in clinical decision making in patients with shoulder instability. The typical lesions related with classic anterior and anteroinferior shoulder dislocation are an anteroinferior labral avulsion with or without bony fragment of bone loss – a (bony) Bankart lesion – and a posterolateral humeral head impaction fracture – the Hill-Sachs lesions. These are relatively straightforward to identify on imaging, although normal variants of the inferior labrum and variants of labral damage may cause confusion. Other capsuloligamentous lesions, often associated with less typical types of instability, are much more difficult to identify correctly on imaging, as they occur in the anterosuperior part of the glenohumeral joint with its many normal variants or because they result in more subtle, and therefore easily overlooked, changes in morphology or signal intensity. This paper aims at describing the appearance of the normal and pathologic glenohumeral joint related to shoulder instability. Ample reference will be given as to why identification of abnormalities, whether normal or pathologic, is important to the surgeon facing a treatment decision.

Advanced Imaging of Glenohumeral Instability: It May Be Less Complicated than It Seems

Glenohumeral joint instability is usually an intimidating topic for most radiologists due to both the complexity of related anatomical and biomechanical considerations and the increasing number of classifications and acronyms reported in the literature in association with this condition. In this short review, we aim to demystify glenohumeral instability by first focusing on the relevant anatomy and pathophysiology. Second, we will review what the important imaging findings are and how to describe them for the clinician in the most relevant yet simple way. The role of the radiologist in assessing glenohumeral instability lesions is to properly describe the stabilizing structures involved (bone, soft-tissue stabilizers, and their periosteal insertion) to localize them and to attempt to characterize them as acute or chronic. Impaction fractures on the glenoid and humeral sides are important to specify, locate, and quantify. In particular, the description of soft-tissue stabilizers should include the status of the periosteal insertion of the capsulo-labro-ligamentous complex. Finally, any associated cartilaginous or rotator cuff tendon lesion should be reported to the clinician.

Artifacts and pitfalls in shoulder magnetic resonance imaging

Magnetic resonance imaging has revolutionized the diagnosis of shoulder lesions, in many cases becoming the method of choice. However, anatomical variations, artifacts and the particularity of the method may be a source of pitfalls, especially for less experienced radiologists. In order to avoid false-positive and false-negative results, the authors carried out a compilation of imaging findings that may simulate injury. It is the authors' intention to provide a useful, consistent and comprehensive reference for both beginner residents and skilled radiologists who work with musculoskeletal magnetic resonance imaging, allowing for them to develop more precise reports and helping them to avoid making mistakes.

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.

Diagnostic value of US, MR and MR arthrography in shoulder instability

INTRODUCTION

The aim of our study was to compare US, conventional MRI and MR arthrography findings in patients with anterior shoulder instability and with a clinical diagnosis of labral capsular ligamentous complex lesion. At the same time we evaluated the accuracy of MR arthrography in the diagnosis of this lesion.

METHODS

After approval of the local Ethics Committee, our department's Trauma Registry from July 2008 up to February 2012 was retrospectively reviewed to identify all eligible patients. Eligibility criteria included: 1)history of acute or chronic shoulder instability (more than three dislocations over a period of more than two months); 2) diagnosis of labroligamentous lesion. All patients were investigated with plain radiographs, Ultrasound Scans (US), Magnetic Resonance Imaging (MRI) and MR arthrography. Finally, all patients underwent an arthroscopy that confirmed the diagnosis.

RESULTS

A total of 200 consecutive patients who met the inclusion criteria were included in this study. The mean age was 39 years (range 15 to 83); 147 were male and 133 involved the right shoulder. Chronic instability was documented in 133 patients, whereas acute instability was documented in 67 patients. We detected a statistically significant difference between US and MR arthrography in SLAP (Superior Labrum Anterior to Posterior) lesions (TypeII, III and IV), in Bankart lesions, in glenohumeral ligament lesions (superior, middle, anterior-inferior and anterior inferior glenohumeral ligament) in Hill-Sachs lesions, in diagnosing internal subacromial impingement and in normal findings. MR arthrography was superior to the US. A statistically significant difference was evident between MRI and MR arthrography findings in SLAP lesions (III and IV Type lesions), in glenohumeral ligament lesions (anterior inferior and posterior inferior glenohumeral ligament), in partial rotator cuff ruptures and in normal findings. MR arthrography diagnosed this lesion better than MRI without contrast. We also found a statistically significant difference between US and MRI findings in SLAP Type II lesions, in partial rotator cuff ruptures, in Hill-Sachs lesions and in diagnosing internal subacromial impingement.

CONCLUSION

The US scan is a valuable diagnostic technique for rotator cuff complete or incomplete ruptures. For evaluating Hill-Sachs lesions or bony Bankart lesions, MRI is more accurate. In the case of labral capsular ligamentous complex lesions, MR arthrography is superior.

Sublabral clefts and recesses in the anterior, inferior, and posterior glenoid labrum at MR arthrography

PURPOSE

To determine the prevalence of a normal variant cleft/recess at the labral-chondral junction in the anterior, inferior, and posterior portions of the shoulder joint.

MATERIALS AND METHODS

One hundred and three consecutive patients (106 shoulders) who had a direct MR arthrogram followed by arthroscopic surgery were enrolled in this IRB-approved study. Scans were carried out on a 1.5-T scanner with an eight-channel shoulder coil. The glenoid rim was divided into eight segments and the labrum in all but the superior and anterosuperior segments was evaluated by two radiologists for the presence of contrast between the labrum and articular cartilage. We measured the depth of any cleft/recess and correlated the MR findings with surgical results. Generalized estimating equation models were used to correlate patient age and gender with the presence and depth of a cleft/recess, and Cohen's kappa values were calculated for interobserver variability.

RESULTS

For segments that were normal at surgery, a cleft/recess was present within a segment on MR arthrogram images in as few as 7 % of patients (within the posteroinferior segment by observer 1), and in up to 61 % of patients (within the posterosuperior segment by observer 1). 55-83 % of these were only 1 mm deep. A 2- to 3-mm recess was seen within 0-37 % of the labral segments, most commonly in the anterior, anteroinferior, and posterosuperior segments. Age and gender did not correlate with the presence of a cleft/recess, although there was an association between males and a 2- to 3-mm deep recess (p = 0.03). The interobserver variability for each segment ranged between 0.15 and 0.49, indicating slight to moderate agreement.

CONCLUSION

One-mm labral-chondral clefts are not uncommon throughout the labrum. A 2- to 3-mm deep smooth, medially curved recess in the anterior, anteroinferior or posterosuperior labrum can rarely be seen, typically as a continuation of a superior recess or anterosuperior labral variant.

The use of ultrasound in the assessment of the glenoid labrum of the glenohumeral joint. Part I: Ultrasound anatomy and examination technique

The glenohumeral joint is a spherical articulation with a remarkable range of motion in several planes and decreased stability. The maintenance of joint stability is influenced by the functioning of specific muscle groups in the shoulder region, a complex system of ligaments reinforcing the joint capsule, and the labrum which augments the glenoid fossa. Lesions of the aforementioned structures require accurate diagnosis prior to a decision for operative treatment. Ultrasound is one of the imaging methods that has been widely used in the assessment of various shoulder pathologies. In the author opinion, this imaging modality may also be applied for the evaluation of labral tears. Being attached along the glenoid rim, the labrum forms a collar deepening the glenoid fossa thus increasing area of its contact with the head of the humerus. To better describe the location of lesions, the glenoid labrum is usually divided into certain zones. Most of them may be visualized sonographically. The US examination of the posterior labrum can be performed during evaluation of the infraspinatus and teres minor muscles. The anterior labrum along with capsulolabral complex is seen at the glenoid edge under the subscapularis tendon. Sonographic examination of the inferior labrum is best performed using axillar approach. The superior labrum is only partially available for US examination. A crucial part of the sonographic assessment of the labrum is the dynamic examination during rotation of the upper extremity. The paper presents normal sonographic anatomy of the glenoid labrum and technique of the examination.

FIESTA: an MR arthrography celebration of shoulder joint anatomy, variants, and their mimics

Magnetic resonance (MR) arthrography is currently the gold standard radiological investigation for shoulder joint instability. Not only does this investigation allow for identification of important disease processes, but the reduced slice thickness and increased in-plane resolution allowed by the latest imaging sequences also gives excellent demonstration of shoulder joint internal anatomy. This article describes the technique of MR arthrography of the shoulder practiced at our institution, briefly outlining features of the FIESTA (fast imaging employing steady state acquisition) MR sequence employed, including its advantages and limitations. A pictorial review of shoulder MR arthrography performed with this technique is presented, concentrating on normal shoulder joint internal anatomy and anatomical variants that may mimic pathology.

Shoulder MR imaging normal variants and imaging artifacts

The appearance of osseous, labral, hyaline cartilage, ligament, muscle, and tendon variants and pitfalls are discussed with attention to the keys to distinguishing each of the findings from pathologic lesions of the shoulder.

Imaging shoulder instability in the athlete

Athletes who partake in overhead or throwing activities frequently suffer from shoulder pain. Glenohumeral instability plays an important role in sports-related shoulder pain. Shoulder instability can be traumatic, atraumatic, or microtraumatic in origin. In athletes, atraumatic and microtraumatic instabilities can lead to secondary impingement and chronic damage to intra-articular structures. MR arthrography is the modality of choice for assessing glenohumeral instability and diagnosing labroligamentous injuries. This article reviews imaging of instability-related injuries in athletes, with special emphasis on MR imaging.

Glenohumeral instability associated with Buford complex

Buford complex is described as a normal anatomical variant of the anterosuperior part of the glenoid consisting of the absence of the anterosuperior labrum with the presence of a cord-like middle glenohumeral ligament. Traditionally, reattachment to the glenoid has been discouraged. We present a case of a Buford complex associated with glenohumeral instability. The patient was operated for recurrent instability without a preoperative diagnosis of Buford complex. The diagnosis was made during shoulder arthroscopy and reattachment to the glenoid was performed with a satisfactory outcome. Here, we discuss the relationship of the Buford complex with intraarticular pathology and the surgical treatment in cases when this variant is associated with instability.

Comparison study of indirect MR arthrography and direct MR arthrography of the shoulder

OBJECTIVE

To compare the diagnostic value of indirect magnetic resonance arthrography (I-MRA) with that of direct MR arthrography (D-MRA) for labral tears, rotator cuff tears, and long head of biceps tendon (LHBT) tears using a 3-T MR unit.

MATERIALS AND METHODS

Institutional review board approval was given; written informed consent was obtained from all patients. From November 2005 to June 2006, 19 patients (eight men and 11 women; mean age, 51 years) who had undergone both I-MRA and D-MRA underwent arthroscopic surgery. Both methods were performed in fat-saturated axial, coronal oblique, and sagittal oblique T1-weighted sequences, as well as axial and coronal oblique T2-weighted sequences. Two radiologists independently and retrospectively evaluated two sets of MRA for the diagnosis of superior and anterior labral tears, subscapularis tendon (SSC), and supraspinatus-infraspinatus tendon (SSP-ISP) tears, and LHBT tears. With the arthroscopic finding as a gold standard, we analyzed statistical differences of sensitivities and specificities between two sets of MRA and inter-observer agreement was evaluated using the kappa value.

RESULTS

The sensitivity and specificity of I-MRA and D-MRA for reader 1 were 79/80% and 71/80%, respectively, for superior labral tears; 100/100% and 100/100%, respectively, for anterior labral tears; 64/75% and 64/100%, respectively, for SSC tears; 100/86% and 100/100%, respectively, for SSP-ISP tears; and 67/100% and 78/100%, respectively, for LHBT tears. Those of I-MRA and D-MRA for reader 2 were 86/80% and 71/100%, respectively, for superior labral tears; 100/83% and 100/100%, respectively, for anterior labral tears; 64/88% and 82/100%, respectively, for SSC tears; 92/86% and 100/100%, respectively, for SSP-ISP tears; and 78/90% and 89/100%, respectively, for LHBT tears. No significant differences were found between the methods. Inter-observer agreements were higher than moderate (kappa > 0.41) with both methods.

CONCLUSIONS

Based on a relatively small number of patients, no significant difference was detected between I-MRI and D-MRI with regard rotator cuff, labral, and LHBT tears.

Clinical update: MR imaging of the shoulder

Magnetic resonance imaging has become an important diagnostic adjunct in the evaluation of shoulder conditions, and the technology continues to evolve. Direct magnetic resonance arthrography can improve detection of labral and rotator cuff pathology, especially partial thickness tears of the rotator cuff. Special positioning, such as abducted-externally rotated views, improves visualization of the rotator cuff and posterior superior labrum in throwing athletes. Diagnosis-specific sequencing such as fat suppression, spin-echo and proton-density techniques, and higher power magnets (3.0 T) allow for an unprecedented level of soft tissue detail. Clinical expertize is required to differentiate between normal anatomic variants, incidental findings, and true pathology. Although magnetic resonance imaging findings may be diagnostic in some cases, clinical correlation with history and physical examination findings is critical.

The usefulness of virtual MR arthroscopy as an adjunct to conventional MR arthrography in detecting anterior labral lesions of the shoulder

OBJECTIVE

The objective of this study was to investigate the usefulness of virtual MR arthroscopy as an adjunct to conventional MR arthrography in detecting various anteroinferior glenoid labral lesions.

MATERIALS AND METHODS

The study group was composed of 28 patients (22 men and six women; mean age, 25 years) who underwent direct MR arthrography of the shoulder as well as arthroscopy due to recurrent shoulder dislocations. MR arthrography examinations were reviewed retrospectively with radiologists blinded to the arthroscopic diagnoses. Virtual MR arthroscopy was produced from fat-suppressed 3D gradient-recalled echo MR arthrography using volume-rendering software. The sensitivity, specificity, and accuracy for diagnosis were calculated. The diagnostic performances were validated by receiver operating characteristic curve analysis.

RESULTS

The structure of the glenoid labrum was well visualized in a 3D perspective, and characterization of the injured anterior glenoid labrum was aided by adjunct use of virtual MR arthroscopy. The accuracy for detecting classic Bankart, anterior labroligamentous periosteal sleeve avulsion, and Perthes lesions improved to 85.7%, 85.7%, and 92.9%, respectively, with adjunct virtual MR arthroscopy with MR arthrography versus 78.6%, 82.1%, and 89.3%, respectively, with MR arthrography alone. A statistically significant improvement of the diagnostic capability of MR arthrography with adjunct virtual MR arthroscopy was proven for the detection of a classic Bankart lesion (p < 0.05).

CONCLUSION

Having a 3D perspective to validate chronic recurrent glenoid labral injuries of the shoulder facilitated understanding of the anatomic relationships and helped diagnosis. Adjunct virtual MR arthroscopy is potentially useful for detecting and characterizing chronic recurrent glenoid labral lesions to improve diagnosis.

MRI of shoulder instability

The most unstable joint in the body, the glenohumeral joint is subject to many insults including microinstability, subluxation and dislocation. During the last two decades, MRI has allowed for direct visualization of many of the lesions related to instability, aiding in diagnosis as well as therapeutic planning and follow-up. This article reviews the use of MRI for shoulder instability and describes the different types of lesions associated with this disorder. Topics include technical considerations, the use of MR arthrography, normal anatomy and variants, labral and glenohumeral ligament pathology, and osseous lesions related to instability.

Physical examination and magnetic resonance imaging in the diagnosis of superior labrum anterior-posterior lesions of the shoulder: a sensitivity analysis

PURPOSE

The overall purpose of our study was to examine the sensitivity of physical examination, magnetic resonance imaging (MRI), and magnetic resonance (MR) arthrogram for the identification of arthroscopically confirmed SLAP lesions of the shoulder.

METHODS

An analysis of 51 consecutive patients with arthroscopically confirmed SLAP lesions and no history of shoulder dislocation was performed. Before undergoing surgery, all patients underwent a standardized physical examination and had either an MRI and/or MR arthrogram performed. Sensitivity analysis was then performed on the results of both the physical examination maneuvers and the radiologic imaging compared to the arthroscopic findings at surgery.

RESULTS

The sensitivity of O'Brien's (active compression) test was 90%, whereas the Mayo (dynamic) shear was 80% and Jobe's relocation test was 76%. The sensitivity of a physical examination with any 1 of these 3 SLAP provocative tests being positive was 100%. Neer's sign (41%) and Hawkin's impingement tests (31%) each had low sensitivity for SLAP lesions. The sensitivity of MRI for SLAP lesions was 67% when interpreted by the performing surgeon, 53% when read by a radiologist. When the MR arthrograms were analyzed alone, the sensitivity was 72% (surgeon) and 50% (radiologist), respectively.

CONCLUSIONS

All 3 physical examination maneuvers traditionally considered provocative for SLAP pathology (O'Brien's, Mayo shear, and Jobe's relocation) were sensitive for the diagnosis of SLAP lesions. MRI and MR arthrogram imaging had lower sensitivity than these physical examination tests in diagnosing SLAP lesions. Patient history, demographics, and the surgeon's physical examination should remain central to the diagnosis of SLAP lesions.

LEVEL OF EVIDENCE

Level II, development of diagnostic criteria on basis of consecutive patients with universally applied gold standard.

First-time shoulder dislocation: High prevalence of labral injury and age-related differences revealed by MR arthrography

PURPOSE

To evaluate abnormalities and age-related differences after first-time shoulder dislocation.

MATERIALS AND METHODS

MRA images of first-time dislocators were assessed for labral-ligamentous-capsular / rotator cuff abnormalities and analyzed the age-related differences (< and >/=30 years old).

RESULTS

Sixty-six patients (34 <30 years old vs. 32 >/=30 years; 51 males; all anterior dislocations) were imaged. Forty-eight patients (73%) showed anteroinferior labral avulsion, consisting of: 6% (4/34 vs. 0/32) Perthes; 23% (8/34 vs. 7/32) free ALPSA (anterior labrum periosteal sleeve avulsion) lesion); 6% (1/34 vs. 3/32) adherent ALPSA; 23% (9/34 vs. 6/32) Bankart; 14% (5/34 vs. 4/32) inferiorly displaced avulsed labrum; 2% (1/34 vs. 0/32) GLAD. Extensive labral detachment (extended above 3 o'clock position) was present in 31% (11/28 vs. 4/20). There were 14% (6/34 vs. 3/32) superior labrum anterior-posterior (SLAP) lesion; 27% (1/34 vs. 17/34) rotator cuff tendon tear; 71% (25/34 vs. 22/32) Hill-Sachs defect. Young patients were more likely to have extensive labral avulsions (P = 0.054), but less likely to have rotator cuff tears (P < 0.001).

CONCLUSION

A high prevalence and wide variety of labral avulsions after first-time shoulder dislocation, especially adherent ALPSA, inferiorly displaced avulsed labrum, or GLAD lesion, may influence treatment choice and outcome, suggesting a role for early MRA to assist in treatment triage.

Técnica e indicaciones de la resonancia magnética artrografía. Extremidad superior (I)

Magnetic resonance (MR) is the most effective imaging technique in the diagnosis of articular pathology. MR arthrography (MRA), with intra-articular injection of diluted gadolinium or physiological saline solution has become more common in recent years. The intra-articular fluid facilitates the detection of articular pathology by delineating the articular structures, separating adjacent anatomic structures, and filling potential spaces that originate in or communicate with the joint. MRA provides additional information about the integrity of the articular structures, especially cartilage, fibrocartilage, and ligaments. MRA has proven especially useful in the shoulder, where most of the studies have been centered. The detection of subtle lesions of the capsule/labrum complex is fundamental for presurgical evaluation. MRA can be used to complement conventional MR imaging in some cases and in others it is the initial technique of choice. Indirect MRA with intravenous gadolinium administration is based on the enhancement of articular fluid caused by diffusion from the synovial space to the articular space. This technique offers better results in articulations with less capacity for distension, such as the wrist, ankle, hand, and foot. This first part of two-part article reviews the current role of MRA in the upper limb. Special emphasis is placed on the shoulder joint, where its usefulness has been most clearly established. The usefulness of this technique in other joints is also described, reviewing the most important anatomic aspects, techniques and applications.

Normal anatomy and common labral lesions at MR arthrography of the shoulder

MR arthrography of the shoulder is the most accurate imaging modality in demonstrating abnormalities of the glenoid labrum and associated structures. Tears of the labrum, the capsule or the gleno-humeral ligaments can lead to pain, catching, popping or instability. The anatomy of this region is complex. We present the normal anatomy of the glenoid labrum, biceps anchor and gleno-humeral ligaments together with their normal variants and then describe common labral-ligamentous pathologies.

Magnetic resonance imaging accuracy for the diagnosis of superior labrum anterior-posterior lesions in the community setting: eighty-three arthroscopically confirmed cases

Magnetic resonance imaging (MRI) has been shown in the literature to have high accuracy for the diagnosis of superior labrum anterior-to-posterior (SLAP) lesions. However, these studies have been performed at specialized institutions and have not been evaluated for community settings. Our hypothesis was that MRI diagnosis of SLAP lesions in the community setting is not as accurate as suggested by previous literature. The MRI reports for 83 consecutive surgically confirmed type II SLAP lesions were evaluated. The findings regarding the presence of SLAP lesions were documented from the community radiologists' MRI readings. Two blinded, fellowship-trained musculoskeletal radiologists evaluated these same 83 MRIs, as well as 17 MRIs with surgically confirmed normal superior labra. The musculoskeletal radiologists also used a visual analog scale to subjectively grade the quality of each MRI. MRIs were performed at 14 different centers and were read by 28 different community radiologists. There were 37 noncontrast MRIs and 46 MRI arthrograms. The community radiologists accurately identified 51% of the SLAP lesions. The sensitivities for the community radiologists were significantly better for the MRI arthrograms than for the noncontrast MRIs (P = .0002). For the two musculoskeletal radiologists, the sensitivities were 60% and 67.5%, and the specificities were 71% and 76.5%. The accuracies for the musculoskeletal radiologists were 62% and 69%. One of the musculoskeletal radiologists had significant correlation between the visual analog score and MRI diagnostic accuracy (P = .0006). The sensitivity for one of the musculoskeletal radiologists was significantly greater than the sensitivity for the community radiologists (P = .0063). The accuracies between the other musculoskeletal radiologist and the community radiologists were not significantly different (P = .0577). In this community setting, MRI was not accurate for the diagnosis of SLAP lesions. Musculoskeletal radiologists were more accurate than the community radiologists; however, the musculoskeletal radiologists were not as accurate as previous literature might predict.

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.

An overview of MR arthrography with emphasis on the current technique and applicational hints and tips

Magnetic resonance (MR) arthrography has been investigated in every major peripheral joint of the body, and has been proven to be effective in determining the integrity of intraarticular ligamentous and fibrocartilaginous structures and in the detection or assessment of osteochondral lesions and loose bodies in selected cases. Several methods could be used to create arthrogram effect during MR imaging, however, direct MR arthrography using diluted gadolinium as the contrast agent is the most commonly used technique and is the most reliable of all. MR arthrography is useful for demonstrating labrocapsular-ligamentous abnormalities and distinguishing partial thickness rotator cuff tears from focal full thickness tears in the shoulder, identifying or excluding recurrent tears following meniscal operations in the knee, demonstrating perforations of the triangular fibrocartilage complex (TFCC) and ligaments in the wrist, showing labral tears in the hip, diagnosing ligament tears in the ankle and identifying osteochondral lesions or loose bodies in any of the aforementioned joints. In this article, an overview of techniques of MR arthrography is provided with emphasis on direct MR arthrography using diluted gadolinium as the contrast agent. The current applications of the technique in major peripheral joints are reviewed, with emphasis given to the shoulder joint where the role of this technique has become well established.

Variants of the superior labrum and labro-bicipital complex: a comparative study of shoulder specimens using MR arthrography, multi-slice CT arthrography and anatomical dissection

The purpose of the present study was to evaluate the anatomical variability of the superior labrum and to compare the value of MR arthrography and multi-slice CT arthrography in the diagnosis of variants of the labro-bicipital complex. Forty-three human shoulder specimens (age range and mean age at death, 61-89 years and 78.3 years) were examined with the use of MR arthrography and multi-slice CT arthrography prior to joint exploration and macroscopic inspection of the superior labrum and labro-bicipital complex. Two radiologists evaluated MR and CT arthrograms, and the results were compared with macroscopic assessments. Anatomical dissection of all shoulder specimens revealed a sublabral recess in 32/43 (74%) cases. The attachment of the superior labrum was categorised as type 1 in ten (23%) cases, as type 2 in eight (19%), as type 3 in ten (23%), and as type 4 in 14 (33%) cases. One superior labrum showed detachment consistent with a superior labral anteroposterior (SLAP) type 3 lesion. On MR arthrography and CT arthrography the attachment of the superior labrum was categorised in concordance with macroscopic assessments in 79% and 84% of cases, respectively. The anteroposterior extension of sublabral recesses was accurately determined with MR and CT arthrography in 59% and 81% of cases, respectively. The attachment of the superior labrum shows considerable variability. Thus, exact depiction of variants is essential in order to avoid the false positive diagnosis of a superior labral tear (SLAP or Andrews lesion). Both, MR arthrography and multi-slice CT arthrography were effective in the detection and classification of sublabral recesses.

Anterior-inferior labral lesions of recurrent shoulder dislocation evaluated by MR arthrography in an adduction internal rotation (ADIR) position

PURPOSE

To introduce and evaluate the usefulness of the adduction internal rotation (ADIR) position in MR arthrography for discriminating the following subtypes of Bankart lesions: classic Bankart lesions, anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesions, and Perthes lesions.

MATERIALS AND METHODS

The study group consisted of 25 patients who had been referred for MR arthrography of the shoulder and then underwent arthroscopy due to recurrent episodes of shoulder dislocation. MR arthrography was performed in three different positions: neutral, abduction external rotation (ABER), and ADIR. The authors evaluated the statistical significance of the method's discriminative diagnostic ability for the subtypes of Bankart lesions according to the position changes.

RESULTS

Twenty-three patients had the following single or complex labral lesions: classic Bankart (N = 8), ALPSA (N = 3), complex classic Bankart/ALPSA (N = 8), and complex ALPSA/Perthes (N = 4). Two patients had no visible anteroinferior labral lesions. The performance of ADIR positioning for differentiating ALPSA lesions was superior to the neutral or ABER positioning. The difference of the discriminative lesion detection ability was statistically significant (P <.01) only for detecting ALPSA lesions in the ADIR position.

CONCLUSION

MR arthrography in the ADIR position provides high accuracy for the diagnosis of ALPSA lesions, and complements routine MR arthrography when used to diagnose labroligamentous lesions in patients with recurrent shoulder dislocations.