Detection of acromioclavicular joint pathology in asymptomatic shoulders with magnetic resonance imaging.

The purpose of this study was to determine the prevalence of acromioclavicular joint (ACJ) arthritis with magnetic resonance imaging (MRI) evaluation in asymptomatic patients. Fifty shoulders in 42 patients were evaluated with the use of standard MRI techniques. There were 18 men and 24 women with an average age of 35 years (range, 19 to 72). ACJ arthritic changes were graded on a scale from 1 to 4 (none, mild, moderate, and severe), based on the amount of subacromial fat effacement, joint space narrowing, irregularity, capsular distension, and osteophyte formation. Forty-one (82%) of 50 shoulders had abnormalities consistent with arthritis on MRI. Patients were divided into two groups according to age: those older than 30 years and those 30 years old or younger. In the 30-and-under age group, 68% of the shoulders had arthritic changes, whereas in the over-30 age group, 93% had arthritic changes. Furthermore, in a comparison of the two groups, more advanced arthritic changes were found in the over-30 age group (P <.05). Clinical decisions to resect the ACJ should correlate the physical examination with the MRI findings because many patients may be clinically asymptomatic.