A study of the synovial and ligamentous structure of the anterior cruciate ligament.

The synovial and ligamentous structure of 16 human anterior cruciate ligaments (ACL), removed at autopsy, were examined by light microscopy with special regard to their topographical relationships. The soft tissue support of the ACL consists of fibrous, areolar and areolo-adipose synovial tissue. The subsynovial layer comprises a tight fibrous peripheral part and an element of loose connective tissue containing some tight connective tissue strands, vessels and nerves. The collagenous ligamentous part of the ACL is the proper functional tissue and contains approximately 1500 fascicles measuring an average of 250 micron in diameter. These fascicles are composed of bundles of collagen fibres, fibrocytes and deposits of proteoglycans. The synovial and ligamentous structures are attached by the second part of the subsynovial layer, which radiates into the ligamentous tissue and envelops the fascicles like a sheath. By this means the biological connection between these two structures is guaranteed. The relevance of these findings to operative reconstruction of recent ligamentous injuries is discussed.