Classic history and presentation: Many individuals have asymptomatic AC joint arthritis, seen incidentally on x-rays. This condition can become painful in patients who have been working overhead, pushing / pulling heavy loads, throwing, or swimming. A single impact, as from a fall, to an AC joint with pre-existing arthritis can also flare pain.
Patients present with pain and/or a clicking or catching sensation on the "top" of their shoulder that worsens with cross-body movement and overhead activity, and may wake them from sleep when rolling onto the affected side. Pain improves with rest by unloading the upper extremity and using it near the body.
Patients may also have pain around the scapula from muscle strain, or at the mid-upper arm, referred from the rotator cuff.
Prevalence: Joint degeneration increases with age. Symptoms appear predominantly in individuals in their 40s.
- Heavy loading of the shoulder, especially overhead or pushing / pulling
- Prior clavicle fracture
- Prior AC separation
- AC joint instability
- Inflammatory arthropathy
Grade / classification system: No generally accepted classification system is used for AC joint arthritis. Most practicing physicians simply classify this as mild, moderate, or severe, which is somewhat subjective.