Abstract
In 1972, Neer II noted that the slope of the acromion of the scapula may play an important role in development of the impingement syndrome of the shoulder joint. This study was undertaken to know the relationship between the slope of the acromion and rotator cuff impingement.
65 intact bleached skeletal bones,130 shoulders (65 right shoulders,65 le f t shoulders) which have been stored in the Department of Anatomy (Section 2), Sapporo Medical College were used. The age and sex of these specimens were clearly known. The undersurface of the acromion and the greater tuberosity of the humeral head were observed to know whether degenerative changes such as a spur formation was present or not. At the same time, the slope of the acromion in the scapular plane was determined.
There was significant variation in the slope of the acromion. Degenerative changes on the undersurface of the acromion located in anterior one-third of the acromion. The incidence of degenerative changes in the undersurface of the acromion increased in accordance with flattening of the slope of the acromion.There was no difference in the slope of the acromion by age, but the incidence of degenerative changes on undersurface of the acromion increased by age. The degenerative changes on the greater tuberosity occured more frequently in the aged shoulders.
These results suggest that the flattened slope of the acromion may be a c ause of subacromial impingement between the anterior part of the acromion and the greater tuberosity. And repetitiv, e stress of subacromial impingement by aging may result in the degenerative change on the undei-surface of the acromion. We think that with growth in the degenerative changes on the undersurface of the acromion, rotator cuff tear may occur, then the degenerative change on the greater tuberosity may appear.
