[Role of the subacromial space on development of the impingement syndrome. I].

In the first part of the study reported in this paper the anatomy of 150 scapulae was studied to find out whether variation in the subacromial space might cause impingement syndrome. Sixteen different parameters, including various angles, size and shape of the acromion and the coracoid process, and length of the coracoacromial ligament and the acromion, were measured. Soft tissue was completely removed from the bone, so that no statement on the rotator cuff was possible. The data were processed using the Tukey LSD test. A statistically significant correlation between the size of the shoulder blade and the length of the acromion and the coracoacromial ligament was found. The shape of the coracoid process showed more individual variations, and no correlation with the size of the bony scapula was found. The shape of the subacromial space was obtained by using four different bony landmarks (acromial angle, tip of the anterior rim of the acromion, tip of the coracoid process and supraglenoid tubercle). Three different types were found: a "rhomboid" in 103 cases, an approximate "kite" shape in 35 cases, and a triangle in 12 cases. The rhomboid form means a larger plane surface, so that the rotator cuff can glide more smoothly than with the other types. The different shapes of the subacromial space did not influence the slope of the acromion in the scapular plane.