Shoulder instability is most commonly seen in adolescents and young adults. It is often the result of sporting activities where the shoulder has experienced direct trauma. Most shoulder dislocations result in the humeral head displacing anteriorly and becoming lodged at the front of the socket.
In most cases, patients will require a visit to the emergency department to have their first shoulder dislocation reduced. This involves administration of a sedative or light anaesthetic and the shoulder joint is then manipulated back into position.
When a shoulder joint dislocates, the rim of cartilage around the socket is often damaged. This tissue is called the labrum and acts almost like a tyre surrounding the rim on wheel. It has the effect of increasing the surface area of the socket and provides stability for shoulder movement. If the labrum has been pushed from the edge of the socket, this predisposes the patient to having further instability or dislocations.
Following a first-time dislocation in an adolescent, there is a high probability that the patient will have further dislocation in the future in the course of normal sporting activities.
Following an acute dislocation, the arm is often rested in a sling to allow the acute discomfort to gradually subside. Most patients are able to start mobilising again within the first three weeks after the dislocation.
Physiotherapy may help strengthen the shoulder girdle musculature but the underlying damage to the labrum and supporting structures around the shoulder joint may lead to the development of recurrent dislocations or a sensation of instability. Some patients will be quite apprehensive with certain movements due to a sensation of instability.
In some cases, patients will progress to the situation where the shoulder dislocates with even normal day-to-day activities such as dressing or elevating their arm above the head.
Surgical options for shoulder instability focus on trying to restore the anatomy and recreate support at the front of the socket. In many cases of 'avulsion' (tearing away) of the labrum, this can be reduced into place with a keyhole procedure.
Each case needs to be assessed in detail with an MRI scan before embarking on any surgical intervention. In some instances, a larger open approach may be required to reinforce the soft tissues and provide stability.