[Morphometry of the sub-acromial space and its clinical relevance]

Rupture of the rotator cuff is one of the commonest (30%) pathologic findings in elderly dissecting room subjects. Together with the degenerative tendopathy associated with increasing age, this is due to mechanical damage to the distal parts of the tendons or the soft tissues lying in the subacromial space between the acromion, coracoacromial ligament, coracoid process and humeral head. The object of this investigation was to examine the influence of the decisive metrical parameters of the subacromial space in the macerated scapula. For this purpose, defined distances and angles of 343 macerated human scapulae were measured by means of an image analysing system, and the results evaluated statistically. It was found that the size of the subacromial space depends, not only upon variations in the form of the acromion itself, but also upon the acromial and scapula-spine angles. Marked projection of the coracoid process, which is dependent upon both the angle between the long axis of the scapula and the root of the coracoid process and the coracoid angle, plays an important part in the development of the so-called subcoracoid impingement syndrome: a constriction of the subscapularis tendon between the coracoid process and the head of the humerus. A clinical assessment of the absolute size of the subacromial space should take into account the size of the body; but sex, age, and the side involved are of little significance.