[Ultrasonography of the shoulder: the acromioclavicular joint]

In 95% of the patients complaining of shoulder pain, pain is consequent to mechanical impingement of the coraco-acromial arch on the rotator cuff. Acromioclavicular joint conditions play a major role (well over 50%) in initiating the process. This study was aimed at assessing the value of acromioclavicular investigations during shoulder US studies. September 1992 to September 1993, a hundred and seventy-four patients with shoulder pain underwent US exams of both shoulders and acromioclavicular joints. In 62% of patients rotator cuff tears (from less to more severe) were demonstrated, in 48% biceps tendon conditions (effusion, tendonitis, dislocation or tear) and in 31% aspecific degenerative changes of the rotator cuff. Three acromioclavicular joint cysts, a clavicular fracture and an acromioclavicular dislocation were also observed. The patients with US patterns of acromioclavicular conditions were 105 (60%); in 38% of cases, only capsular hypertrophy due to joint degeneration was observed. In 22% of cases the latter was associated with arthrosis-like changes of the articular rim. In 63% of cases rotator cuff tears were associated and in 37% of cases there were aspecific degenerative cuff changes. The authors believe that, especially in the latter cases, acromioclavicular joint US can be a useful approach to diagnosis and treatment.