SCJ Injury

A sternoclavicular joint (SCJ) injury is a sprain, subluxation or dislocation of the joint between the medial clavicle and the sternum, ranging from minor to life-threatening.

SCJ injuries are uncommon. Anterior dislocation is far more common than posterior and is usually managed without surgery. Posterior dislocation is rare but can be life-threatening, because the trachea, oesophagus and great vessels lie directly behind the joint.

The medial clavicular physis can stay open until around 25, so in adolescents and young adults an apparent dislocation is often a physeal fracture-separation.

The SCJ is a saddle-shaped synovial joint between the medial clavicle, the manubrium and the first costal cartilage. It is the only true bony joint between the upper limb and the axial skeleton. An intra-articular disc divides it into 2 compartments.

Stabilisers:

• •The posterior capsule: the most important restraint to both forward and backward translation
• •The anterior capsule: a further restraint to forward translation
• •The costoclavicular (rhomboid) ligament: restrains upward and lateral displacement
• •The interclavicular ligament: restrains upward displacement

Directly behind the joint lie the trachea and oesophagus, the great vessels (brachiocephalic vein, aortic arch branches and common carotid artery), the brachial plexus, and the recurrent laryngeal, phrenic and vagus nerves.

Mechanisms:

• •Anterior dislocation: usually an indirect blow to the back of the shoulder, such as a tackle or a fall onto the point of the shoulder
• •Posterior dislocation: a direct blow to the front of the medial clavicle, or compression across both shoulders (a scrum collapse, a pile-up, a motorcyclist thrown forwards)
• •Atraumatic instability: generalised hypermobility or repetitive overhead activity

The Allman classification grades the injury: grade I sprain, grade II subluxation, grade III complete dislocation (anterior or posterior).