The acromioclavicular joint is located at the shoulder's top. It connects acromion and clavicle. Its main function is to help moving the scapula and the arm.
Overuse or muscle tear can cause the acromioclavicular joint sprain. The common injuries include: ligament sprains, torn ligaments, joint disruption. Other complications may include: chronic pain, arthropathy, arthritis, skin abrasions or bursa infections.
Some sports (e.g. football, basketball, tennis or badminton, etc.) often cause acromioclavicular sprains. These sports make the acromioclavicular joint prone to injury, due to excessive stretching or excessive colliding force.