A cadaveric study of the structural anatomy of the sternoclavicular joint.

Pathologies of the sternoclavicular (SC) joint are infrequent and effective management is often hindered by a limited understanding of the anatomy. In this study, we did macroscopic evaluations of the ligaments, the intra-articular disc, and the articulating surfaces of 25 SC joints. After removal of the joint capsule, the articulating surfaces of the sternal end of clavicle and the sternum were evaluated and the intra-articular disc was macroscopically examined. The anterior SC ligament covered the intra-articular disc, which divided the joint into a clavicular and a sternal part. A thin capsule, relatively lateral and medial from the anterior SC ligament, covered the two intra-articular parts. This means that the anterior SC ligament can be used as a landmark to enter into clavicular or sternal part of the SC joint. Posteriorly, there was a thick capsule without soft-spot or clear posterior SC ligament. Only the antero-inferior surface of the sternal end of every clavicle was covered by cartilage. Of the intra-articular discs 56% were incomplete. All of these incomplete discs displayed a central hole with signs of degeneration and fraying. This was associated with increased cartilage degeneration at the clavicular side. By experimental design (past and present), it would seem reasonable to assume that the incomplete types are caused by degeneration and are not developmental.