Faculty Bibliography

OBJECTIVE: To create 3DMR osseous models of the shoulder similar to 3DCT models using a gradient-echo-based two-point/Dixon sequence. MATERIALS AND METHODS: CT and 3TMR examinations of 7 cadaveric shoulders were obtained. Glenoid defects were created in 4 of the cadaveric shoulders. Each MR study included an axial Dixon 3D-dual-echo-time T1W-FLASH (acquisition time of 3 min/30 s). The water-only image data from the Dixon sequence and CT data were post-processed using 3D software. The following measurements were obtained on the shoulders: surface area (SA), height/width of the glenoid and humeral head, and width of the biceps groove. The glenoid defects were measured on imaging and compared with measurements made on en face digital photographs of the glenoid fossae (reference standard). Paired t tests/ANOVA were used to assess the differences between the imaging modalities. RESULTS: The differences between the glenoid and humeral measurements were not statistically significant (cm): glenoid SA 0.12 +/- 0.04 (p = 0.45) and glenoid width 0.13 +/- 0.06 (p = 0.06) with no difference in glenoid height measurement; humeral head SA 0.07 +/- 0.12 (p = 0.42), humeral head height 0.03 +/- 0.06 (p = 0.42), humeral head width 0.07 +/- 0.06(p = 0.18), and biceps groove width 0.02 +/- 0.01 (p = 0.07). The mean/standard deviation difference between the reference standard and 3DMR measurements was 0.25 +/- 0.96 %/0.30 +/- 0.14 mm; 3DCT 0.25 +/- 0.96 /0.75 +/- 0.39 mm. There was no statistical difference between the measurements obtained on 3DMR and 3DCT (percentage, p = 0.45; mm, p = 0.20). CONCLUSION: Accurate 3D osseous models of the shoulder can be produced using a 3D two-point/Dixon sequence and can be added to MR examinations with a minor increase in imaging time, used to quantify glenoid loss, and may eliminate the need for pre-surgical CT examinations.

Anatomic reconstruction of the humeral head with osteochondral allograft has been reported as a solution for large Hill-Sachs lesions with or without glenoid bone loss. However, to date, varying techniques have been used. This technical note describes an arthroscopic reconstruction technique using fresh-frozen, side- and size-matched osteochondral humeral head allograft. Allograft plugs are press fit into the defect without internal fixation and seated flush with the surrounding articular surface. This technique restores the native articular contour of the humeral head without compromising shoulder range of motion. Potential benefits of this all-arthroscopic approach include minimal trauma to the soft tissue and articular surface without the need for hardware or staged reoperation.

OBJECTIVE: To evaluate the degree and location patterns of subscapularis tendon injury in patients with prior anterior shoulder dislocation (ASD). MATERIAL AND METHODS: Forty-five consecutive MR shoulder examinations in patients with a history of ASD and 20 consecutive MR examinations in patients without prior dislocation were reviewed. Two readers assessed for the presence and location of tendinosis and tearing in the subscapularis tendon, which was divided into three segments: superior, middle, and inferior. The readers also documented the presence of anterior labral tears, osseous Bankart defects and Hill-Sachs lesions. Fisher's exact tests were performed to analyze the different types of pathology and their locations. RESULTS: Subscapularis tendinosis, and partial thickness and full thickness tears were more common in patients with a history of ASD. Tendinosis was found in 60-64.4% of the dislocation patients compared with 40% of the non-dislocation group. When stratified by location, the middle and inferior thirds were the most commonly affected with statistical significance (p < 0.05) found in tearing of the inferior third. Anterior labral tears, osseous Bankart defects, and Hill-Sachs lesions were more common in the dislocation group with statistically significant associations with tendinosis in the middle and inferior thirds and tearing of the middle third (p < 0.05). CONCLUSION: Our study suggests an association between middle and inferior subscapularis tendon pathology and prior anterior shoulder dislocation. Based on our results, careful MR assessment of the subscapularis tendon by the radiologist is indicated in the setting of ASD as injury of this structure can be symptomatic and may be amenable to treatment.

OBJECTIVE: The purpose of this study is to assess the accuracy of MRI quantification of glenoid bone loss and to compare the diagnostic accuracy of MRI to CT in the measurement of glenoid bone loss. MATERIALS AND METHODS: MRI, CT, and 3D CT examinations of 18 cadaveric glenoids were obtained after the creation of defects along the anterior and anteroinferior glenoid. The defects were measured by three readers separately and blindly using the circle method. These measurements were compared with measurements made on digital photographic images of the cadaveric glenoids. Paired sample Student t tests were used to compare the imaging modalities. Concordance correlation coefficients were also calculated to measure interobserver agreement. RESULTS: Our data show that MRI could be used to accurately measure glenoid bone loss with a small margin of error (mean, 3.44%; range, 2.06-5.94%) in estimated percentage loss. MRI accuracy was similar to that of both CT and 3D CT for glenoid loss measurements in our study for the readers familiar with the circle method, with 1.3% as the maximum expected difference in accuracy of the percentage bone loss between the different modalities (95% confidence). CONCLUSION: Glenoid bone loss can be accurately measured on MRI using the circle method. The MRI quantification of glenoid bone loss compares favorably to measurements obtained using 3D CT and CT. The accuracy of the measurements correlates with the level of training, and a learning curve is expected before mastering this technique.

Traumatic dislocation of the shoulder is a frequent injury in the young and active population. An acute shoulder dislocation often denotes a onetime traumatic episode, whereas chronic shoulder instability indicates multiple recurrent dislocations. Imaging, in particular MRI, is a useful tool that can accurately demonstrate the typical soft tissue and osseous markers of shoulder dislocation. However, the ability to differentiate between first time versus recurrent dislocation based on imaging remains in question. In this article, we describe the underlying biomechanics of glenohumeral stability as well as the imaging features and treatment options of shoulder dislocation. A review of current literature is presented, aimed to shed light about the potential role of imaging in distinguishing first dislocation versus chronic instability.

MRI has been shown to be both sensitive and specific in the diagnosis of partial thickness and full-thickness tears of the rotator cuff. Recognizing the pattern of a rotator cuff tear before surgery also provides useful information to the referring clinician as it can help in the selection of the type of surgery and lead to a better anatomic and biomechanical restoration of the cuff tendons. There is relative paucity of published reports exploring the performance of MRI in the recognition and classification of rotator cuff tears based on their morphological pattern. The purpose of this exhibit is: 1) to describe the geometric patterns of rotator cuff tears, 2) to illustrate the MR imaging appearance of the different patterns of rotator cuff tearing, 3) to describe the clinical significance of the different patterns in terms of treatment selection and outcome prediction. Characterization of the most common rotator cuff tear patterns will be presented including: crescent-shaped, U-shaped, L-shaped, and massive cuff tears. This will be followed by a guide that can be used to recognize these patterns on MRI utilizing the location as well as the size of the transverse and longitudinal components of the tear on surgically proven cases. Finally, a review of the different types of repairs currently available for each tear pattern will be presented including end-to-bone repair and margin convergence techniques as well as the expected postsurgical outcomes

Purpose: To create a guide for the radiologist to help him/her learn how to recognize and interpret normal anatomy and basic pathology on arthroscopic images using MRI. Materials/Methods: We will give an introduction to shoulder arthroscopy and compare its strengths/weaknesses to MRI. The arthroscopy introduction will include a description of the patient positions used during surgery, portals used, and a roadmap that will help the radiologist navigate through the shoulder anatomy on the surgical images. Normal anatomy and pathology will be presented on arthroscopic and MR images from the same patient, providing direct comparison and contrast of the two modalities. Results: The viewer will review the following normal anatomy on arthroscopy and MRI: biceps anchor/tendon, labrum, glenoid and humeral cartilage, articular and bursal rotator cuff, rotator interval/ biceps pulley, and acromioclavicular joint. This will be followed by a review of common shoulder pathologies, including: SLAP tears, anterior labral tear, GLAD lesion, bicep's pulley lesion, full-thickness rotator cuff tear, osseous Bankart lesion, and Hill-Sachs lesion. Conclusion: The goal for this presentation is to familiarize the radiologist with the basics of shoulder arthroscopy with special attention to the appearance of normal anatomy and common pathology. This will hopefully lead to an improved understanding of the relationship between these two imaging modalities and the common pathologies that inflict the shoulder

The rotator cable, an extension of the coracohumeral ligament, is a fibrous band-like structure that courses along the undersurface of the supraspinatus and infraspinatus tendons perpendicular to their tendon fibers. Originally described in the orthopaedic literature, the rotator cable likely plays an important role in the biomechanics of the intact and torn rotator cuff. Published data addressing the performance of MR imaging in the evaluation of the rotator cable is rather limited. The purpose of this exhibit is threefold: 1) to describe the normal gross anatomy, histology, as well as the MR imaging anatomy of the rotator cable, 2) to describe the role of imaging as it pertains to the cable's function in the biomechanics of the intact and torn rotator cuff, 3) to underscore the clinical significance of the cable in terms of classification and treatment of rotator cuff tears. Introduction to the most current knowledge on the origin, distribution, and insertions of the rotator cable using gross anatomy, histology, and MR imaging correlation will be presented. Emphasis will be placed on the MR appearance of the rotator cable in orthogonal imaging planes in both intact and torn rotator cuffs. The role of the rotator cable in the setting of rotator cuff pathology will be underscored using MRI, including its potential contributions to the geometric configuration of cuff tears, altered glenohumeral biomechanics, and fatty degeneration of the rotator cuff musculature. Lastly, a review of the clinical importance of the rotator cable will be provided focused on the effect of the cable's integrity in the management of rotator cuff tears

The rotator cable is an extension of the coracohumeral ligament coursing along the undersurface of the supraspinatus and infraspinatus tendons. The rotator cable is thought to play a role in the biomechanical function of the intact and torn rotator cuff. It can be seen on all the imaging planes used for the conventional magnetic resonance imaging of the shoulder. Clinically, the integrity of the rotator cable can play a role in the treatment selection for patients with a rotator cuff tear.