Shoulder Anatomy

The shoulder is the most mobile joint in the body. The shoulder joint is similar to a ball-and-socket joint that is comprised of three main bones: the collarbone (clavicle), the shoulder blade (scapula) and the upper arm bone (humerus), which extends from the shoulder blade to the elbow. The upper end of the humerus where it rotates is a smooth, rounded head (ball) that fits into the glenoid cavity (socket) of the shoulder blade. Because the ball is larger than the socket, it is more flexible, but has less inherent stability.

Muscles, tendons and connective tissue protect the shoulder joint and hold the various parts together. Because the shoulder joint is stabilized by muscles and tendons, rather than by bone, the shoulder has great flexibility. This gives the shoulder joint a wide range of motion enabling movements such as lifting, pushing and pulling.

However, this great degree of motion has a trade off; the stability of the shoulder is dependent upon the surrounding soft tissue and can result in a larger number of problems not faced by other joints supported by bony structures. A healthy shoulder can be damaged by disease or injury, resulting in severe pain, pseudoparalysis (false paralysis) and muscle weakness.

Pain is one of the key reasons people consider joint replacement surgery. Intense pain can also limit your range of motion and prohibit you from performing your normal day-to-day activities or getting a good night’s rest. Your doctor may recommend non-surgical treatments initially; however, if conservative treatment has failed to provide you any relief, surgical options may be considered.