Anatomic variation of the coracoacromial ligament: a macroscopic and microscopic cadaveric study

The operative management of the subacromial impingement syndrome includes reconstruction in cases with ruptured tendons and enlargement of the subacromial space by arthroscopic or open resection of the coracoacromial ligament and acromioplasty. In nearly 20% of all cases, however, surgical treatment fails. This study was conducted with 124 cadaver shoulders of older specimens with a balanced male/female ratio. The coracoacromial ligament did not present homogenous morphologic characteristics. We found 25.8% of all ligaments undivided, 59.7% bipartite, and 14.5% consisted of three parts. The third part, located most medially, took a hidden path to the coracoid process and was not visible during dissection until after the clavicle was resected. This medially situated third part of the coracoacromial ligament has not been described in the medical literature before the time of our investigation. It could well be responsible for persisting subacromial pain after surgery, if it is not identified and resected during surgery.