Osteoarthritis of the acromioclavicular joint – colloquially called acromioclavicular joint arthrosis – (synonyms: Acromioclavicular joint arthrosis; AC joint arthrosis; ACG arthrosis; ICD-10-GM M19.-: Other osteoarthritis) is a degenerative disease of the acromioclavicular joint. It refers to wear and tear of the articular cartilage. The acromioclavicular joint, also called the AC joint, is located between the acromion (roof of the shoulder) and the outer portion of the clavicle (collarbone). Thus, the acromioclavicular joint is part of the shoulder joint.
Normally, the cartilage, together with the synovial fluid (synovia), protects the joints and acts as a kind of “shock absorber”. Due to osteoarthritis, this function can no longer be guaranteed.
Osteoarthritis of the acromioclavicular joint can be divided into “primary forms” – e.g., due to overuse – and “secondary forms” – due to malformations, diseases, trauma (injury), surgery, etc:
- Primary osteoarthritis of other joints: shoulder region [acromioclavicular joint] (ICD-10-GM M19.01).
- Posttraumatic osteoarthritis of other joints: shoulder region [acromioclavicular joint] (ICD-10-GM M19.11)
- Other secondary osteoarthritis: shoulder region [acromioclavicular joint] (ICD-10-GM M19.21)
- Other secondary osteoarthritis: shoulder region [acromioclavicular joint] (ICD-10-GM M19.81)
- Osteoarthritis, unspecified: Shoulder region [acromioclavicular joint] (ICD-10-GM M19.91)
Frequency peak: the disease occurs predominantly from the 5th decade of life. Approximately every person over 50 years of age is affected by osteoarthritis of the acromioclavicular joint. Clinical symptoms are detectable in very few of them.
Sex ratio: Men are more frequently affected than women.
Course and prognosis: The onset of arthrosis of the acromioclavicular joint is usually insidious. In the course, bony changes caused by the arthrosis can lead to damage to the rotator cuff (group of four muscles whose tendons, together with the ligamentum coracohumerale, form a tough tendon cap that encompasses the shoulder joint) and even to tendon rupture (tendon tear). The condition is not curable, but adequate treatments can significantly alleviate symptoms and prevent progression (progression). If conservative measures do not lead to the desired success, surgery should be performed. As a result, affected individuals are free of symptoms and the shoulder can be moved without deficit.
