抄録
(Purpose) Instability may cause impingement lesions. However, the category of M. D. I. has not been examined yet.
(Materials and Methods) 218 shoulders of 200 patients who had a loose shoulder were investigated.127shoulders underwent conservative treatment, and glenoid osteotomy was performed on 91 shoulders. The range of motion and the painful arc were measured in the motion of anterior elevation, lataral elevation, posterior elevation, horizontal adduction, horizontal abduction and internal and external rotations in the horizontal plane.
(Results) The percentages of pain appearance rate with each motion indicated 18.1%, 28.3%, 18.9%, 21.3%, 22.8%, 22.0%, 26.0% in the non-operative group and 24.3%, 23.1%, 25.3%, 20.9%, 22.0%, 31.9%, 19.8% in the operative group. Each value decreased to 5.5%, 6.6%, 4.4%, 3.3%, 5.5%, 13.2%, 8.8% post-operatively. The arthrograms of each subject did not detect any rotator cuff tears.
(Discussion) The painful arc in the motions of internal and external rotation in the horizontal plane and the motion of horizontal adduction look similar to the impingement sign advocatedby Neer and Howkins. According to our results, between 20% and 30% of the patients with a loose shoulder showed a positive, impingement sign. However, the rate of the painful arc in other motions indicated the same level as the rate of impingement sign which could detect a subacromial impingement lesion. In addition, no cuff tears could represent any actual subacrimial friction. On the other hand, glenoid osteotomy made the glenoid articular surface tilt anteriorly and superiorly. Although the effect of this tilting may cause a subacromial impingement, the rate of impingement decreased after surgery. Therefore, in a loose shoulder, the impingement sign does not always imply the existance of a subacromial impingement. Improvement of instability, not a subacromial decompression should be the advocated treatment for this painful arc.
