The humoral head is the rounded surface on the proximal end that articulates with the glenoid cavity. This shallow ball-and-socket joint allows for a large range of motion but also makes the joint more susceptible to dislocation. The heads of the humerus and the glenoid are both covered by articular cartilage to facilitate joint movement.
The surface of the humoral head can be damaged by injury or disease, such as arthritis. In some cases, a total shoulder replacement or total shoulder arthroplasty (TSA) is needed. This is a surgical procedure in which the entire humeral head and neck is replaced by a metal implant. A mating plastic cup is placed in the glenoid cavity of the scapula. An alternative implant is the “reverse” total shoulder replacement, where the ball is attached to the scapula and the cup is implanted in the end of the humerus. This arrangement mimics the function of the rotator cuff muscles and is commonly used to treat people whose muscles are not functioning properly.
