Sternoclavicular Joint

Introduction

Diarthrodial saddle joint incongruous (~50% contact)
- fibrocartilage (not synovial cartilage)
- contains an intra-articular disc
Motion
- elevation of arm to 90° leads to rotation of the sternoclavicular joint of 30°
Imaging
- best assessed radiographically by Serendipity view
  - involves 40° cephalic tilt view of sternum and clavicle
  - CT scan is most sensitive and specific

Stabilizing Ligaments of Sternoclavicular Joint

Posterior sternoclavicular capsular ligament
- primary restraint for anterior-posterior stability
Anterior sternoclavicular ligament
- primary restraint to superior displacement of medial clavicle
Costoclavicular (rhomboid) ligament
- anterior fasciculus resists superior rotation and lateral displacement
- posterior fasciculus resists inferior rotation and medial displacement
Intra-articular disk ligament
- prevents medial displacement of clavicle
- secondary restraint to superior clavicle displacement

Medial Clavicle Anatomy

Clavicle is the first bone to begin the ossification process
- ossifies between 5th and 6th weeks of gestation
Clavicle is the last bone to complete the ossification process
- medial epiphysis of clavicle is last physis to close at 20-25 yrs
Important to distinguish SC dislocations from physeal fractures
- most injuries at this location involve the medial clavicular physis before age of 25