[Magnetic resonance in the study of the painful shoulder. The surgical comparison in 30 consecutive cases].

Eighty patients complaining of shoulder pain were examined with MRI from January, 1993, through December, 1994. Thirty of them were submitted to surgery, with an exhaustive inspection of shoulder structures and the treatment of abnormal findings. In this subgroup of surgical patients, MRI had depicted 16 complete tears of the rotator cuff, 4 partial tears, 8 cases of subacromial impingement, I humeral head osteochondritis and, finally, I humeral head osteochondritis with complete rotator cuff tear. Surgical findings confirmed MR diagnosis in 97% of cases. MR findings were then compared with literature data and some atypical features were observed in our series. MRI was totally reliable in complete cuff tears (16/30 patients), always showing the involvement of supraspinatus tendons and, in some cases, of other cuff tendons. In partial cuff tears (4/30 patients), besides the classic pattern of a fissure in the deep/superficial supraspinatus tendon, we observed intra- and peritendinous changes, with no tendon interruption, due to diffuse microlesions. When impingement due to subacromial space narrowing, with no cuff tear, was present (8/30 patients), MRI depicted different causes--e.g., acromioclavear arthrosis, coracoacromial ligament hypertrophy and posttraumatic changes. MRI showed tendinosis in all patients but overestimated it in one case where partial cuff tear was not confirmed surgically--the only false positive in our series. At surgery, all these cases were classified as stage I-II impingement (according to Neer's classification). Finally, MRI was very reliable in the study of bone conditions (osteochondritis), both isolated and associated with cuff tears. The diagnostic accuracy of MRI in the study of the painful shoulder was very high (97%), in agreement with literature data. This is very important because many different causes of shoulder conditions (abnormal tendons, bones and mechanics) may present with similar clinical symptoms. MRI appears as the only imaging method yielding complete and accurate pieces of information in the patients with a painful shoulder.