UPDATE IN SHOULDER MAGNETIC-RESONANCE-IMAGING

The shoulder is capable of the largest range motion of any articulatio n in the human body. Because it is inherently unstable, the glenohumer al joint is dependent on the support given by surrounding muscular, li gamentous, and tendonous structures. A variety of disorders may involv e these structural supports and lead to shoulder pain and dysfunction. Refinements in magnetic resonance (MR) imaging techniques have allowe d improved characterization of these abnormalities and may permit earl ier and more specific diagnoses in patients with shoulder pain. Theori es as to the pathogenesis of rotator cuff disease include intrinsic an d extrinsic impingement as well as overload tendinosis. MR is useful i n the evaluation of rotator cuff impingement and tears. The classifica tion and MR assessment of glenohumeral instability has recently receiv ed increased attention yet remains an area of difficulty. MR arthrogra phy has been used with some success in the evaluation of instability d emonstrating improved diagnostic sensitivities and specificities when compared with conventional MR. Relatively little attention has been pa id to MR evaluation of the shoulder after surgery. Micrometallic artif act, distortion of soft-tissue planes, and persistent signal abnormali ties within rotator cuff and capsulolabral structures may hinder asses sment of recurrent tear or instability in the postoperative patient.