Management of the Unstable Shoulder

The shoulder is the most commonly dislocated joint in the human body. The incidence of dislocation is increasing. Recurrence rates can be up to 90 percent in people under the age of 21 that play contact sports. The incidence rate is approximately 2.8 %.

How should a shoulder that keeps dislocating be clinically assessed?

A history and examination are the cornerstones of treating this condition. Historical questions such as:

• Was you first dislocation caused by a specific injury?
  
• How old were you when you had your first dislocated shoulder?
  
• How many times has your shoulder dislocated?
  
• In which direction does your shoulder dislocate? (Anteriorly in more than 90% of cases).

Answering these questions will go a long way to working out whether this can be managed with conservative treatment or needs to be managed surgically.

What investigations are performed?

Standard x-rays of the shoulder (anterior/posterior and axillary views) should be undertaken when instability is suspected. X-rays are useful for identifying defects of the glenoid and humeral head. The Hills-Sachs lesion is a posterolateral depression of the humeral head that arises from impact against the anterior rim of the glenoid.

Your specialist may order an MRI scan to check for damage of the rotator cuff, glenoid labrum and glenohumeral ligaments. The labrum is an important stabilising structure that may be avulsed from the glenoid rim, resulting in a Bankart lesion. This can be an important cause of recurrent dislocations.

What treatment is recommended for recurrent dislocation?

Non-surgical management is indicated for all those with a muscle patterning component. This is often the case with a first time dislocations that have had very little damage to the joints and the soft tissue. Two weeks in a sling, followed by a strengthening program over 6-8 weeks can often result in a strong and stable shoulder. Referral for a surgical opinion is recommended at 3 months if sufficient progress is not being made during a rehabilitation program.

Surgical management is indicated when instability is either purely structural or persists despite physiotherapy. There are two main strategies available to repair a dislocated shoulder. These can be soft tissue or bony blocks. Bony blocks are a relatively new treatments and involve reinforcing the glenoid rim with an extra structure and is recommended in young rugby players, due to the decrease rate of re-dislocation in this group. There is also some debate on whether a soft tissue repair should be done open through a keyhole approach. In a prospective randomised control trial comparing the two methods, the risk of recurrent dislocation was significantly lower after an open repair (1)

What is the long-term outcome of patients with an unstable shoulder?

Left untreated, an unstable shoulder will continue to dislocate, even after surgery. Approximately 26% of patients will exhibit recurrent instability at 35 years. Arthritis of the shoulder joint occurs in 55% of patients at 25 years, and therefore a common long-term sequelae.

Many thanks to the British Journal of Sports Medicine: Management of the Unstable Shoulder.