Acromioclavicular (AC) joint arthritis typically occurs in two types of patients: the younger collision or overhead contact athletes in their 30s or in those who are in middle age with wear and tear around the AC joint over time.
Patients usually present with pain over the top of the shoulder exacerbated by placing the affected arm across the body and trouble sleeping on the affected side.
AC joint arthritis may occur with other conditions in the shoulder and therefore it requires careful workup and investigation to exclude subacromial bursitis, shoulder spurs, shoulder impingement, biceps tendonitis, biceps tendon tears, SLAP tears, supraspinatus tendon tears and subscapularis tendon tears.
The Acromioclavicular Joint (ACJ) is formed by the end of the collar bone as it approaches the roof of the shoulder (acromion). With repeated trauma or as we age the ACJ may degenerate, lose cartilage, and narrow leading to arthritis. In most cases ACJ arthritis is not painful and is an incidental diagnosis.
The most common form of ACJ arthritis is osteoarthritis; but it may also occur due to trauma, inflammatory arthritis, and infection. ACJ arthritis is a common finding in patients who present with shoulder impingement syndrome and rotator cuff tears.
In younger patients, repeated microtrauma over many years of sport (collision sport, weightlifting) or manual work may lead to painful ACJ arthritis. These patients often have isolated ACJ arthritis and the remainder of the shoulder is essentially normal.
Older patients who present with shoulder impingement, rotator cuff tears, and shoulder arthritis often have ACJ arthritis in addition to many other areas of pain generation in the shoulder.
The Risk factors for ACJ arthritis are:
Most patients with ACJ arthritis present with pain and tenderness directly over the ACJ Joint. If the joint has been injured previously (such as during collision sports or weightlifting) then there may also be a lump of bone over the AC Joint which causes a prominence.
The pain is generally worse with the affected arm taken across the body or lying on the affected side (as these compress the AC Joint). The pain may also be exacerbated with overhead activity or when lifting heavy things overhead.
In some cases, the presentation is more vague with pain radiating to the neck, chest, side of the shoulder or down the arm.
The examination involves inspection for changes around the AC Joint, direct palpation, provocation tests and assessment of a range of motion.
Imaging the diagnosis is often made on plain X-ray, this demonstrates narrowing of the joint and/or extra bone formation. It is important to exclude other changes around the shoulder, such as shoulder impingement, shoulder spur, and shoulder joint arthritis. An MRI scan may be done and will confirm the diagnosis and exclude other concomitant conditions, such as rotator cuff tears and biceps tendonitis.
In most cases, the initial treatment for ACJ arthritis is non-surgical; it may take weeks or months to notice gradual improvement and return to function. The principles around non-surgical treatment include rest, activity modification,non-steroidal anti-inflammatory drugs (NSAIDs), and supervised physiotherapy. An ultrasound guided cortisone injection is very effective with both diagnosis and treatment of AC Joint arthritis. Such injections may provide relief for anwyere between a few weeks to a few months. Generally it is best not to have more than two injections per year.
If your condition does not improve with nonsurgical treatment, then surgery may be an option for you. Surgery may also be a better option if you have other associated shoulder problems, particularly those that are time urgent.
The surgery is arthroscopic (keyhole) and involves taking a small portion of bone out of the end of the collar-bone (about 6-8mm in total) to clear up the space: this is called an AC Joint Resection (also called AC Joint excision arthroplasty).
If you are unable (even after a period of rest and activity modification) to participate in your chosen leisure activity or sport and you wish to continue to do so.
AC Joint arthritis is not time urgent and most patients can manage with non-surgical treatment; however, there is no cure for it without surgery and this will not heal itself. There are some places that offer PRP injections to treat the AC Joint arthritis, but the evidence around this is limited.
The key ways to prevent AC Joint arthritis is to minimise collison sports or overhead work over a lifetime. Outside of this, a supervised physiotherapy program to strengthen the rotator cuff, deltoid, and scapula stabilising muscles will help minimise the pain from ACJ arthritis.
This 48 year old gentleman presented with pain over the top of his shoulder over many months. A diagnosis of AC Joint arthritis was made and he responded well to an ultrasound guided cortisone injection initially. However, that wore off over a few months and he was unable to sleep on the affected shoulder and very keen to get back to his active lifestyle, so he elected to proceed with surgery.
He underwent an Arthroscopic Acromioclavicular Joint (ACJ) excision via 3 small keyhole incisions. His procedure was routine, he stayed overnight in hospital, and was discharged home the following morning with oral painkillers.
He commenced immediate range of motion and discarded his sling between 1 -2 weeks after surgery. At three months, he is back to the gym and kayaking and is happy with his outcome; his keyhole incisions were only barely visible at the 3 month follow up.
Arthroscopic AC Joint excision is a very successful operation when non-surgical measures have been exhausted.
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