Anatomic and functional aspects of the kinetics of the shoulder joint capsule and the subacromial bursa.

This anatomic study was devoted to the kinetics of the shoulder joint and especially the subacromial region. Following dissection of the shoulder joint capsule and subacromial region of 80 unpreserved shoulder joints, the anatomic relationships of the subacromial space in the neutral position and in continuous abduction (30 degrees, 60 degrees and 90 degrees with fixed scapulae) were examined. These investigations were supplemented by histologic preparations. In the course of our examinations we discovered a gliding mechanism of the subacromial bursa. Moreover, we found a subcoracoid attachment of the shoulder joint capsule and a precoracoid ligamentous connection running between the short head of the biceps brachii m. and the coracoacromial ligament. We termed this the coracoid aponeurosis, which facilitates gliding behaviour of the shoulder joint capsule beneath the coracoid process. In view of this gliding mechanism of the subacromial bursa and the coracoid aponeurosis, discovered in the course of our investigations, we have to reassess the kinetics of the sub-acromial and subcoracoid space. Further, we should reconsider our operative technique in cases of the subacromial or subcoracoid impingement syndrome.