The costoclavicular ligament is the strongest and most important ligament of the sternoclavicular joint, connecting the first rib to the inferior clavicular surface in a rhomboid pattern. It resists upward and lateral clavicular displacement, making it the primary restraint against the distracting forces of shoulder loading. Its disruption in SC joint dislocation allows the clavicle to displace anteriorly or posteriorly.
| Origin | Cartilage and bone of the first rib |
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| Insertion | Inferior surface of the medial clavicle |
| Actions | Primary stabiliser of the sternoclavicular joint against superior and lateral clavicular displacement; limits clavicular elevation and protraction |
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The costoclavicular ligament must be reconstructed in SC joint stabilisation surgery for persistent instability after dislocation. Its strong attachments make it resistant to injury in most shoulder girdle trauma, as clavicle shaft fractures are far more common than SC joint dislocations.
Costoclavicular ligament disruption producing sternoclavicular joint instability requiring ligament reconstruction for anterior instability and urgent reduction for posterior dislocation.
