AC JOINT DISLOCATION (Shoulder Separation)
What is the AC Joint?
The AC Joint is the joint between the outer end of the clavicle (collar bone) and the acromion (tip of the shoulder blade).
How commonly is it injured?
It is quite a common injury particularly in young sportsmen such as rugby players. About 10% of all shoulder injuries involve this joint.
How is it injured?
Usually by a fall directly on to the point of the shoulder but sometimes by a fall on to the outstretched hand.
How is it diagnosed?
It is quite easily diagnosed on clinical examination when the injury is more severe. For milder forms of injury, an x-ray may be required to make the diagnosis. AC joint separations are graded from mild to severe (Type 1 to type 6). Type 1 is the mildest type of injury. This is a simple sprain of the joint ligaments. A Type 2 injury is more severe and results in the collar bone being displaced slightly upwards. A type 3 injury results in the collar bone being completely separated from the acromion. This results in an obvious bump on examination of the shoulder. Type 4-6 injuries are more severe forms of separation.
How is it treated?
Most people are treated without the need for an operation. This is particularly true for type 1 and 2 injuries and the majority of type 3 injuries. The arm is rested in a sling and regular painkillers and anti-inflammatory drugs are prescribed. The sling is purely for comfort and does not change the rate of healing of the injury. As the pain improves, one can start to use the arm for day to day activities. Physiotherapy is useful to get the shoulder muscles working properly again. By about 3 months most people are back to normal activities including sports with minimal or no symptoms. They are, however, left with a permanent lump over the shoulder due to the persistent dislocation. This does not appear to impair their function.
Who needs an operation?
About 10% of people with type 1-3 injuries continue to have symptoms even after 3 months. These symptoms include persistent pain,and weakness in the shoulder. In these patients surgery should be considered.
A small number of people do not wish to wait for 3 months to see if their symptoms will settle and opt for early surgery to stabilise the joint.
All patients with Type 4-6 dislocations require early surgery.
What does the surgery involve?
For Type 1 and 2 injuries with persistent pain after 3 months, removal of the damaged AC joint is recommended. This is done by keyhole surgery (arthroscopic AC joint excision).
For Type 3,4,5 and 6 injuries the collarbone needs to be aligned with the acromion and held in place. If the injury is less than 3-4 weeks old, then a keyhole or open fixation of the collar bone to the shoulder blade is performed. There are a number of surgical methods available for achieving this. If the injury is more than 3-4 weeks old, then a ligament transfer procedure is recommended in addition to the fixation procedure.
What about post-operative recovery?
A sling will be required for about 3-6 weeks. It must also be worn in bed.For the first 3-6 weeks your sling must be worn in bed. The surgeon sees the patient about 2 weeks after the operation. Physiotherapy starts at about 3 weeks. For the first three weeks most activities such as feeding and dressing must be carried out using the normal arm. Driving is to be avoided for at least 6 weeks. As far as work is concerned, this depend s upon your occupation. Office workers can often return to work at about 3-6 weeks, but manual workers may not be able to return for 3 months.