A PRACTICAL APPROACH TO IMAGING OF THE SHOULDER WITH EMPHASIS ON MR-IMAGING

Imaging has a significant role in the diagnosis and treatment of shoul der abnormalities. Numerous complexities unique to the shoulder make d iagnosis challenging for both the primary care physician and the accom plished surgeon. The evolving knowledge of shoulder biomechanics, impr oved anatomic visualization by arthroscopy, and overlapping symptoms w ith multiple conditions all contribute to the difficulty in clinical d iagnosis. The shoulder is anatomically complex with numerous structure s contributing to both the mobility and stability of the joint. Variat ions of normal anatomy can lead to confusion during arthroscopic diagn osis and treatment. Diagnostic imaging, especially MR imaging, clarifi es some diagnostically difficult scenarios by demonstrating both intra -articular and extraarticular anatomy. The dynamic elements of glenohu meral and scapulothoracic muscle force couples contribute to shoulder stability and mobility. MR imaging, in particular, provides an accurat e assessment of muscle anatomy and status. A spectrum of disorders of the shoulder with overlapping clinical presentations can be extrinsic and intrinsic to the joint. The accurate diagnosis of pain in the shou lder caused by cervical spine disease, neurovascular disease, or neopl asm that can mimic intra-articular pathology is often aided by the pos itive and pertinent negative findings of imaging. Arthroscopy often de monstrates multiple pathologic lesions during a single evaluation and treatment. More sophisticated methods of imaging in combination with a n accurate history and complete physical examination help to prioritiz e treatment in situations in which multiple options exist. Orthopedic treatment sometimes fails to produce predictable results, questioning the accuracy of diagnosis. This underscores the need for improved imag ing for diagnosis. This article describes the application of available imaging modalities with an emphasis on MR imaging. A strategy for the appropriate use of these studies and their variations of technique is provided.