The Sternoclavicular Joint

Abstract

The SCJ is the only bony connection between upper limb and the axial skeleton. It is the joint with the least bony congruency in the body yet it is extremely stable thanks to a strong stabilising soft-tissue envelope of ligaments, muscles and tendons. Injury and pathology around the SCJ is uncommon.

Instability of the joint is relatively rare and is best classified by Polar Type (Type I: Structural Traumatic, Type II: Structural Atraumatic, Type III: Muscle Patterning). Traumatic subluxation or dislocation of the SCJ usually requires significant force and the Sports Physician should be mindful of associated injuries. Damage or compromise to the posterior mediastinal structures is an ever-present risk with a posterior dislocation and should be considered as a potential medical emergency. Most anterior dislocations and posterior subluxations can be managed non-operatively whilst an acute posterior dislocation, particularly in the presence of mediastinal compromise, may require an open reduction and stabilisation. Atraumatic structural and muscle patterning instability can usually be treated with non-operative measures including anti-inflammatory medication and physical therapy.

Rarely the SCJ disc can be damaged leading to symptoms of clicking and pain in overhead sports. This is sometimes the result of a shearing injury in a normal disc but more commonly due to a tear in a degenerate disc.

Osteoarthritis is relatively common in patients over 50 but usually asymptomatic. When troublesome it can lead to pain, crepitus and clicking at the joint, particularly in overhead sports. Most patients can be treated by non-operative measures.