ACROMIOCLAVICULAR (AC) JOINT PROBLEMS
What is the acromioclavicular joint?
The acromioclavicular (AC) joint is the point where the collar bone (clavicle) meets the flat bone at the top of the shoulder blade, known as the acromion. The joint is located on the tip of the shoulder and moves when your arm is overhead or stretching across your chest. The AC-JOINT is held in position by two ligaments (the coracoclavicular ligaments) and cushioned by a thick pad of cartilage, known as the meniscus.
Acromioclavicular joint problems and injuries are most common in athletes who must carry weight on their shoulders, such as weightlifters, wrestlers and rugby players.
Types of acromioclavicular joint problems:
The three most common conditions that can affect the acromioclavicular joint are arthritis, stress fractures (osteolysis) and dislocations.
- AC-JOINT arthritis:
AC-JOINT arthritis is a degenerative disease that can cause a loss of cartilage around the joint. This can lead to irritation, the development of bony spurs, inflammation and pain around the joint. Arthritis is the most common cause of acromioclavicular joint arthritis. For this reason it is most common in people who are builders and plasterers, who may carry weights overhead, or who are aged 50 or older and in athletes who place a lot of stress on the joint – such as rugby players and weight lifters.
- AC-JOINT stress fractures:
Repetitive overhead activities that put an excessive weight on the edge of the collar bone can lead to erosion or stress fractures (osteolysis). Stress fractures of the AC-JOINT (also known as AC-JOINT osteolysis) can happen at the outer end of the collar bone, at the point where it joins the shoulder blade. AC-JOINT stress fractures are most seen in athletes such as rugby players and weightlifters and in people whose work includes heavy overhead activities, such as builders and plasterers.
- AC-JOINT dislocations:
The AC joint can dislocate or separate just like the shoulder can. It normally happens due to a traumatic injury which causes the ligaments holding the bones of the joint in place to break. The acromioclavicular joint can be dislocated by trauma such a fall directly onto the tip of the shoulder, or by a fall onto an outstretched hand. The degree of dislocation or separation is determined by how many of the ligaments are torn and how far the collar bone has been moved. The severity of the injury can be graded from I-VI.
How are acromioclavicular joint problems diagnosed?
X-rays are the initial choice. A variety of images may be required to assess the degree of AC joint disruption or separation.
How are AC Joint problems treated?
Video Procedure: http://www.youtube.com/watch?v=feORxSQby2Y
There is controversy about the success of surgery versus non-operative intervention for grade III type injuries to the AC joint. Grade I and II injuries and separations of the AC joint seem to respond favorably to conservative treatment. Grade IV, V, and VI separations of the AC joint often require surgical reconstruction.
AC joint injuries
- Types I and II injuries are managed conservatively with ice, a sling for 1-3 weeks and non-steroidal anti-inflammatory drugs (NSAIDs) followed by physiotherapy to strengthen muscles and ligaments after the acute phase.
- Type III injuries should be managed conservatively but carefully selected cases may benefit from surgical intervention if conservative therapy fails.
- Types IV to VI are nearly always treated with open reduction and internal fixation.
- All acute lesions thought to be worse than type II should be referred urgently for an orthopaedic opinion.
AC joint stress fractures or Osteolysis
- Activity modification, physiotherapy and NSAIDs/other analgesia.
- Cortisone injections may provide relief of symptoms for up to three months in expert hands. Currently there is no consensus in terms of dosage, and injections should be limited to fewer than four per year. Duration of analgesia is very variable with ranges of two hours to three months reported.
- In severe cases of OA or osteolysis, removal of the end of the clavicle may need to be considered. This can be performed arthroscopically. In OA, consider surgery for severe cases where there is failure of response to conservative management after six months