Where is the SC joint?
Put a finger on the top of your breastbone (sternum), then slide it sideways toward your shoulder. The bump where your collarbone (clavicle) meets the breastbone is the sternoclavicular joint. It is the only true bony joint between your arm and the rest of your skeleton — everything else (including the shoulder blade) floats on muscle.
How does it get injured in rugby?
- Direct blow to the front of the chest — a knee or shoulder into the SC joint during a tackle or ruck
- Lateral compression of the shoulder — a heavy hit on the outside of the shoulder that drives the collarbone inward
- Falling onto the side of the shoulder with another player landing on top
- Rare in rugby compared with AC joint or collarbone fractures, but consequences can be more serious
Front vs back dislocation — why it matters
The collarbone can pop forward (anterior) or backward (posterior) out of the joint. Front dislocations are more common and usually manageable. Back dislocations push the collarbone toward the windpipe, food pipe, and major blood vessels sitting just behind the joint — that is why a posterior SC dislocation is treated as a medical emergency.
What recovery looks like
Mild sprains usually settle with a sling for comfort and gradual return to movement over 2–4 weeks. Anterior dislocations are sometimes left in their displaced position if stable, because the cosmetic bump is harmless. Posterior dislocations almost always need urgent reduction (manipulation back into place) under specialist supervision because of what sits behind the joint.