A comparison of magnetic resonance imaging findings of the acromioclavicular joint in symptomatic versus asymptomatic patients

The purpose of this study was to compare acromioclavicular (AC) joint magnetic resonance imaging (MRI) findings in asymptomatic patients with those in symptomatic patients. The MRI scans of 25 patients with symptomatic AC joints were compared with 50 asymptomatic control subjects by use of the same grading scale. In the symptomatic group, AC joint arthritis grading was normal in 0%, mild in 20%, moderate in 52%, and severe in 28%. In the asymptomatic group, grading was normal in 18%, mild in 66%, moderate in 12%, and severe in 4%; there was a statistically higher grade of AC arthritis in the symptomatic group (P < .05). Of the symptomatic individuals, 80% demonstrated reactive bone edema in either the distal clavicle (6), the acromion (3), or both sides of the AC joint (11), whereas no individual in the asymptomatic group had this finding (P < .05). Reactive bone edema on MRI is a more reliable predictor of symptomatic AC pathology than degenerative changes seen on MRI and, when correlated with clinical examination, is reproducible.