Sternoclavicular Joint Disc

discus articularis sternoclavicularis

The sternoclavicular joint disc is a complete fibrocartilaginous disc dividing the SC joint into two compartments. It anchors superiorly to the clavicle and inferiorly to the first costal cartilage, acting as the primary stabiliser of the medial clavicle.

Region: Shoulder

Biomechanics

Function & Actions

The SC disc is the primary stabiliser of the SC joint — more important than the capsular ligaments. Resists both medial and superior clavicular displacement, distributes load across the joint, and prevents direct bone-on-bone contact.

Clinical Relevance

Clinical Notes

SC disc degeneration produces medial clavicle pain and swelling, often misdiagnosed as a tumour or infection. The Sabiston procedure removes the medial clavicle including the disc for painful SC arthritis. Disc integrity is critical for SC joint stability — disc avulsion produces the same instability as ligament rupture.

Pathology

Common Injuries & Conditions

SC Joint Disc Degeneration (Friedrich Disease)

Avascular necrosis and degeneration of the SC joint disc producing painful medial clavicle swelling mimicking infection or tumour, managed by disc excision and medial clavicle resection.

SC Disc Avulsion in Physeal Injury

In adolescents, the SC disc attachment may avulse the medial clavicular physis (which fuses last at age 25) rather than the disc itself, producing an epiphyseal equivalent of SC dislocation.