The Acromioclavicular Joint (AC Joint) is the gliding joint that connects the shoulder blade and collarbone. It is capable of numerous positions and is very susceptible to injury.
An AC sprain is a stretching or even tearing of the ligaments that connect the bones together at the joint. Ligaments are bands of tough and fibrous tissue that act like "binders" throughout the musculoskeletal system. A strain-- often called a "pulled muscle" --is a stretching or tearing of muscle tissue.
Strains and sprains are caused by sudden and/or unusual stress on joints or muscles, such as a fall, accident, lifting heavy objects, overexertion or performing an unfamiliar action such as a new sport or work-related task. AC injuries are often sports-related. Chronic, stressful exertion can be a factor. Insufficient "warming up" and stretching of the muscles before heavy physical activity can also result in this type of injury. Risk of sprains and strains increases if a person is in poor physical shape, overweight, and/or unused to physical activity.
Symptoms of AC sprains and strains can include pain, swelling, spasms, tenderness and restricted or painful movement of the affected area.
