Arthritis is a condition where the cartilage, covering two bones which move in a joint, wears off. This is commonly known as wear and tear.
The clavicle (collarbone) and acromion (flat part of the shoulder blade) has a cartilage washer between them called the meniscus.
This washer can also wear out by, on average, age 40. This causes the two bony ends to rub together, which can cause pain and swelling on top of the shoulder joint.
Treatment options include painkillers and cortisone injections to the AC joint, with physiotherapy to prevent further stiffness and help restore joint mobility.
If this conservative approach is not effective and the pain and stiffness persists, surgery may be required.
The operation performed is called a Mumford procedure and can be done using open or arthroscopic (keyhole) surgery.