The AC joint, or acromioclavicular joint, is a small joint located at the top of your shoulder. It connects the end of your collarbone (clavicle) to the acromion, a bony projection from your shoulder blade (scapula). This connection provides crucial stability and movement to your shoulder complex.
Understanding the AC Joint's Role
The AC joint is a gliding or plane-style synovial joint, meaning it allows for a small amount of sliding movement between the clavicle and acromion. This subtle movement is vital for the overall range of motion and function of your shoulder. Think of it as a fine-tuning mechanism for the larger shoulder joint.
- Stability: The joint's primary function is to provide stability to the shoulder, working in conjunction with other ligaments and muscles.
- Motion: While limited, the movement permitted by the AC joint contributes significantly to shoulder flexibility and various arm movements.
Common AC Joint Problems
Several issues can affect the AC joint, leading to pain and dysfunction. Common conditions include:
- Arthritis: Wear and tear of the cartilage within the joint. This causes pain and restricted arm movement.
- Fractures: A broken bone in either the clavicle or acromion, often due to a fall or direct impact.
- Separations: A dislocation of the AC joint, typically caused by a fall, blow, or other trauma. This is a common injury in contact sports. This often involves injury to the ligaments supporting the joint.
The information presented here is based on multiple reputable sources, including Johns Hopkins Medicine, Physiopedia, UpToDate, and others. These sources highlight the importance of the AC joint in shoulder function and common pathologies associated with this joint.
