STERNO-CLAVICULAR JOINT STABILITY – CLINICAL OBSERVATIONS, BIOMECHANICAL TESTING AND OPTIONS FOR IMPROVING SURGICAL STABILISATION

Abstract

Background: Instability of the Sterno-Clavicular Joint (SCJ) can occur due to indirect trauma or ligament laxity. Reconstruction of unstable SCJs has focussed on extra-articular procedures aimed at either holding the medial clavicle downwards or backwards (for anterior subluxation), and often attempting to re-create the Costo-Clavicular CC ligament effect.

Methods: Experience of clinical traumatic injuries where the intra-articular meniscus of the SCJ was disrupted has highlighted the importance of this structure in stabilising the SCJ. This meniscus, through its attachments to the sternum medially and the clavicle laterally, may have a greater effect on the stability of the joint than previously realised – much greater than the stabilising effect of the CC ligament. Anatomical studies of the intra-articular disc, its attachments and the effect of dividing the CC ligament have been carried out on anatomical and fresh frozen cadaver specimens.

Results: Division of the CC ligament alone has only a small effect on SCJ stability. However division of the SCJ disc with the CC still intact has a significant effect on SCJ stability. It is now suspected that patients with joint laxity associated with SCJ anterior subluxation have pathology affecting the SCJ disc and this will be described. An embroidered polyester SCJ augmentation device has been designed to re-create the stabilising forces initially generated by the SCJ disc before stretching or tearing has occurred. This device has been designed to be inserted within the SCJ disc (if present) and anchored to the sternum and clavicle using screws with a technique that recreates stability to the joint. The biomechanics of this reconstruction with pictorial demonstrations of the effect of this stabiliser will be described.

Discussion: Our understanding of the stabilising structures of the SCJ is only now becoming clearer. With this knowledge, improved methods of managing SCJ problems may now be developed.