The sternoclavicular joint (SCJ) is a pivotal
articulation in the linked system of the upper limb girdle, providing
load-bearing in compression while resisting displacement in tension
or distraction at the manubrium sterni. The SCJ and acromioclavicular
joint (ACJ) both have a small surface area of contact protected
by an intra-articular fibrocartilaginous disc and are supported
by strong extrinsic and intrinsic capsular ligaments. The function
of load-sharing in the upper limb by bulky periscapular and thoracobrachial
muscles is extremely important to the longevity of both joints.
Ligamentous and capsular laxity changes with age, exposing both
joints to greater strain, which may explain the rising incidence
of arthritis in both with age. The incidence of arthritis in the
SCJ is less than that in the ACJ, suggesting that the extrinsic
ligaments of the SCJ provide greater stability than the coracoclavicular
ligaments of the ACJ. Instability of the SCJ is rare and can be difficult to distinguish
from medial clavicular physeal or metaphyseal fracture-separation:
cross-sectional imaging is often required. The distinction is important
because the treatment options and outcomes of treatment are dissimilar,
whereas the treatment and outcomes of ACJ separation and fracture
of the lateral clavicle can be similar. Proper recognition and treatment
of traumatic instability is vital as these injuries may be life-threatening.
Instability of the SCJ does not always require surgical intervention.
An accurate diagnosis is required before surgery can be considered,
and we recommend the use of the Stanmore instability triangle. Most
poor outcomes result from a failure to recognise the underlying
pathology. There is a natural reluctance for orthopaedic surgeons to operate
in this area owing to unfamiliarity with, and the close proximity
of, the related vascular structures, but the interposed sternohyoid
and sternothyroid muscles are rarely injured and provide a clear
boundary to the medial retroclavicular space, as well as an anatomical
barrier to unsafe intervention. This review presents current concepts of instability of the SCJ,
describes the relevant surgical anatomy, provides a framework for
diagnosis and management, including physiotherapy, and discusses
the technical challenges of operative intervention. Cite this article:
