#condition - Shoulder

Shoulder Instability

  • The shoulder is one of the most mobile joints in the body.
  • Instability of the shoulder can occur for a variety of reasons.
  • Depending on the instability pattern treatment may require surgery, physiotherapy or both.

What is shoulder instability?

The shoulder is the most mobile joint in the human body. It performs a vital role in allowing us to position our hands in the space around us in order to perform the variety of tasks that we perform during our daily lives. The price to pay for this mobility is that the shoulder is one of the least stable joints in the body.

shoulder girdle

Why does it happen?

The shoulder ( a shallow ball and socket joint) can become unstable after major trauma such as during a fall or tackle where the structures that normally control its stability are torn. In individuals with a high degree of flexibility the shoulder may be inherently lax or become more troublesome after minor or more repetitive injury.

X-ray of an acute shoulder dislocation

X-ray of an acute shoulder dislocation

What structures are damaged in shoulder instability?

The shoulder relies on both anatomical structures, such as the labrum (a ring of cartilage that deepens the socket), joint capsule and ligaments as well as co-ordinated action of the muscles around the shoulder to provide stability. In a traumatic shoulder dislocation the humeral head (ball) is usually dislocated anteriorly (to the front) out of the glenoid (joint socket). This results in tearing of the labrum and damage to the ligaments.

Labrum and glenohumeral ligaments

Labrum and glenohumeral ligaments

This may result in these structures becoming unable to help contain the head in the glenoid in certain arm positions. In some cases the anterior rim of the glenoid can become fractured and this can exacerbate the problem.

What treatments are available for shoulder instability?

The appropriate treatment for shoulder instability is dependant on a number of factors including the type of instability, the pattern of structures injured and the anticipated types and levels of activity that the individual wishes to undertake. In a traumatic instability it may be necessary to repair the damaged structures with either an arthroscopic stabilisation (keyhole surgery) or open procedure.

If the dislocation has occurred without trauma or with only minor trauma or if the age and activity levels of the individual make further dislocation unlikely it may be that the instability can be treated successfully with physiotherapy.