Acromioclavicular (AC) Joint Osteolysis
What is it?
AC Joint osteolysis is essentially a repetitive stress injury of the outer end of the clavicle (collarbone), where it forms the acromioclavicular joint. For understanding the diagram below identifies the shoulder anatomy and its component parts. Osteolysis is another term for bone erosion where the bone is eroded faster than it can be replaced or repaired.
How did I get it?
Excessive activities that load the outer clavicle and AC joint can lead to osteolysis, as the repetitive damage exceeds the ability for the bone to heal after loading. The AC joint is maximally loaded with heavy overhead activities. AC joint osteolysis is therefore more common in strength and power athletes e.g. weightlifters, powerlifters and rugby players. It is also a common injury with those work activities which involve tasks with a high component of overhead work e.g. builders and plasterers.
How is a diagnosis made?
A diagnosis is usually made on the history of injury and location of pain. An x-ray will usually be ordered. Other tests such as CT scans and MRIs are rarely required. The figure below illustrates AC Joint osteolysis as seen on an X-ray.
g. builders and plasterers.
What are the symptoms?
The main symptom of ACJ osteolysis is pain at the top of the shoulder at the AC joint. It usually feels worse with overhead activities such as reaching above your head or reaching across your body. The area is often also sore to touch.
What should I do?
ACJ osteolysis is a painful condition but a relatively safe one. If the pain is bearable it is usually safe to continue activities which are not provoking a greater level of pain. If the pain is severe and you are having to modify your activities then seeking medical attention will be the best option.
What does rehab involve?
Modified activities: Modification of your lifting technique or altering your exercise selection may be all that is required for mild cases. Sometimes using a narrower grip, performing less overhead lifts and avoiding upright rows can be effective.
Anti-inflammatory (NSAIDs) medications and pain-killers may be effective in reducing the pain and inflammation.
Physio/exercise therapy can be useful to further explore activity modification so that you can stay fit and strong without provoking the injury. Physiotherapy may also help provide pain relief to the area.
Injection: a cortisone or synvisc injection with local anaesthetic is often beneficial to reduce pain. The injections usually last for a few months and can provide relief whilst the bone recovers.
Surgery: If the above does not settle the pain, excision of the eroded bone and damaged joint may be considered an option.