Shoulder injuries and different types of arthritis may cause acromioclavicular (AC) joint pain. The AC joint in the shoulder connects the collarbone to part of the shoulder blade. One of the AC ...

Flexion and extension refer to directions of motion that affect the angle of a joint. Flexion is when the joint is closed, while extension is when it is opened. Flexion and extension are the two ...

Painful shoulder conditions, such as shoulder arthritis and rotator cuff tears, are common. Treatments such as medications, physical therapy, and steroid injections can help, but sometimes surgical ...