AAOS Comprehensive Orthopaedic Review 4: Print + Ebook (AAOS - American Academy of Orthopaedic Surgeons)

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Section 6 | Shoulder and Elbow

d. Rotator cuff pathology: The wide spectrum of rotator cuff pathology can be visualized on MRI ( Figure 4 ). • Rotator cuff tears are best visualized on T2-­ weighted sequences. • The amount of tear retraction is best visu alized on coronal plane images. • The width (AP) of the tear is best seen on sagittal reconstructions. • Edema and thickening of the rotator cuff tendon associated with tendinosis can be assessed. • Rotator cuff muscle atrophy and fatty degen eration are best assessed on T1-weighted sagittal sequences at the level of the base of the coracoid process ( Figure 5 ). • Magnetic resonance arthrography: Partial tears may have a bursal-side or articular-­ side location; this may be best determined using magnetic resonance arthrography. Magnetic resonance arthrography is more accurate than conventional MRI in assess ment of postoperative shoulder pathology. e. Pectoralis major rupture: Diagnosis is mostly clinical, but MRI can help distinguish a partial tear from a complete tear ( Figure 6 ). MRI can also be useful in distinguishing distal tendon avulsion from musculotendinous junction tears. Figure 3 Axial T2-weighted magnetic resonance image of the shoulder with intra-articular contrast shows anterior labral pathology. The arrow indicates where contrast fluid has leaked between the glenoid bone and the labral tissue, consistent with a labral tear.

has been shown to be effective in identifying intra-articular long head of biceps pathology. e. Sternoclavicular joint: CT is the imaging modal ity of choice for evaluation of the sternoclavicu lar joint and can be useful to evaluate traumatic injuries as well as degenerative or infectious con ditions of the sternoclavicular joint. It is helpful to distinguish instability from medial clavicular physeal fractures in the adolescent population. Addition of intravenous contrast can be used to assess concomitant vascular injury. 1. Indications a. Bankart lesion: Anterior capsulolabral pathol ogy is best visualized on magnetic resonance image with intra-articular gadolinium ( Figure 3 ). b. Superior labrum anterior to posterior lesion: Magnetic resonance arthrogram is the pre ferred imaging modality for evaluation of superior labrum anterior to posterior lesions. Noncontrast MRI has been shown to have poor sensitivity for superior labrum anterior to pos terior lesions. Clinical correlation and physical examination findings are essential to corrobo rate MRI findings. c. Spinoglenoid cyst: MRI is the diagnostic tool of choice. Ultrasonography of the shoulder has not been shown to be effective in identifying spinoglenoid cysts. Figure 2 Three-dimensional sagittal CT image of the shoulder allows for optimal evaluation of this displaced glenoid fracture. C. MRI

6 | Shoulder and Elbow

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AAOS Comprehensive Orthopaedic Review 4

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