What is shoulder instability?
The shoulder is a ball-and-socket joint, but the socket is shallow — like a golf ball resting on a tee. A rim of cartilage (the labrum) and the surrounding ligaments deepen the socket and hold the ball in place.
Instability occurs when these structures are stretched or torn and can no longer keep the ball centred. The shoulder may partially slip (subluxation) or fully come out of the socket (dislocation) — and once it has happened, it can recur more easily.
Signs and symptoms
- checkA sense the shoulder may “pop out” in certain positions, especially overhead.
- checkRecurrent dislocations or slipping with progressively less force needed each time.
- checkPain and apprehension when the arm is raised and rotated outward.
- checkA loose or “dead-arm” feeling during or after activity.
- checkWeakness and reduced confidence in the joint.
Causes & risk factors
- A previous traumatic dislocation — the most common cause.
- Repetitive overhead sport (throwing, swimming, volleyball).
- Naturally loose ligaments (generalised hypermobility).
- Young age at first dislocation, which raises recurrence risk.
How it is diagnosed
Specific apprehension and relocation tests reproduce the feeling of instability and localise the direction. An MRI — often with contrast (MR arthrogram) — shows labral tears (such as a Bankart lesion) and any associated bone loss, which is critical for surgical planning.
Treatment options
Rehabilitation
Strengthening the rotator cuff and shoulder-blade muscles improves dynamic stability — a sensible first step for first-time, low-demand cases.
Arthroscopic stabilisation
The torn labrum and ligaments are reattached and tightened through keyhole surgery (a Bankart repair) to restore a stable socket.
Bone-block procedures
Where there is significant bone loss, a procedure such as the Latarjet rebuilds the socket’s front edge for durable stability.
Risk-based
Young athletes in collision sports often benefit from earlier stabilisation, given the high chance of recurrence with rehab alone.
Each dislocation can cause a little more damage. In a young athlete, stabilising the shoulder early often protects the joint for the long term.
Recovery & outlook
After stabilisation surgery the arm is supported in a sling, followed by a progressive programme that restores motion, then strength, then sport-specific control. Return to contact sport is typically around four to six months and is guided by regained strength and confidence. Modern arthroscopic repair has a high success rate in preventing further dislocations.