Why do Shoulder Joints dislocate?

Dislocation of a joint is a condition in which the joint surfaces of a particular joint are no longer in contact with each other. Shoulder dislocations happen when the head of the upper arm bone (humerus) moves out from the socket (glenoid cavity).

The socket formed by the glenoid is very shallow, this allows the shoulder great mobility. The shallow socket, however, makes it very susceptible to dislocation compared to other joints. In other to ensure shoulder stability, the socket is deepened by a piece of cartilage known as the labrum and is further stabilised by muscles and ligaments around the joint.

Shoulders can dislocate in 3 directions, with dislocations with the humeral head coming out the front being the most common. We will focus the rest of the article on anterior dislocations of the shoulder.

How do shoulder dislocations happen?

Most anterior dislocations of the shoulder happen with sudden forces exerted on an arm in the cocked position.

This forces the humeral head out of the socket and can cause damage to the labrum and other structures as the dislocation happens. Damage to the labrum, in particular, predisposes a patient to a subsequent dislocation.

In some patients, shoulder dislocations can happen due to lax soft tissues around the shoulder joint. These patients frequently report dislocations happening without any major injury or trauma. It could be caused by something as innocuous as sneezing.

What are some of the symptoms of a Shoulder Joint Dislocation?

Surgical treatment of shoulder dislocations is tied into the risk of recurrence. Isolated dislocated shoulders at low risk of recurrence can usually be treated just with shoulder reduction, a short period of immobilisation (~2 weeks), and subsequent shoulder physiotherapy.

1. Labral repair surgery – the torn labrum is repaired to its original position
2. Bone augmentation procedures – in cases with bone damage or loss from the glenoid
3. Capsular/tendon advancement procedures – in cases where there is bone damage to the humeral head
4. Capsular plication techniques for patients with lax shoulder joints

Rehabilitation and Recovery

Most patients after an initial shoulder dislocation or surgery to fix recurrent dislocations will be asked to undergo a curated course of shoulder rehabilitation. This usually includes shoulder range of motion exercises, and strengthening exercises for the muscles in the shoulder region, with a view to subsequent return to sport. After acute dislocations and or surgery, most patients can return to sport within 6-12 weeks.

For an assessment of your condition, please book an appointment with Dr. Yong Ren.

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