Anatomic variants of the coracoacromial ligament.

Cadaveric anatomic dissections of 50 shoulders have been done with measurement and histologic analysis of the coracoacromial ligament. In subjects older than 50 years of age the coracoacromial ligament does not have a constant form. Three main types were identified: quadrangular, Y-shaped, and a broad band. A previously unreported type of coracoacromial ligament the multiple banded ligament, was found. It had the largest coracoid attachment. This ligament was similar to the Y form but with an additional band extending inferiorly and medially toward the base of the coracoid. Histologic analysis indicates the multiple banded type could be more common than this study suggests.