Coracoacromial ligament: a comparative arthroscopic and anatomic study.

An anatomic study of the coracoacromial ligament was conducted. The data collected from 20 anatomical preparations and the arthroscopic findings in 40 cases were compared. The shape and the tension of the ligament were evaluated, as well as the thickness. Anatomic tradition describes the ligament as a fibrous triangular lamina inserted with its apex on the acromial tip and its base on the lateral edge of the coracoid. It simply closes the coracoacromial arch and has no mechanical role. However, our observations suggest that the ligament has a trapezoidal shape and is situated below the acromion with a wide reflex portion. Its thickness varies from 2 to 5.6 mm. Given that structure, the ligament appears like a robust suspension structure of the coracoid, which contrasts the action of the muscles that connect to it. From these observations, a pathogenic hypothesis of the subacromial impingement proposes itself.