Shoulder Joint Cartilage Injuries: Overview

Shoulder Joint Cartilage Injuries: Overview

The shoulder is a ball-and-socket joint that is the most mobile joint in the body. The ball is formed from the top of the humerus, or upper arm bone, called the humeral head. The socket is formed from the side of the scapula, or shoulder blade, called the glenoid.

The humeral head and glenoid are both lined with articular cartilage, which reduces friction with movement and helps the bones glide smoothly, allowing the arm to move in a wide range of motion. The shoulder joint also has a labrum, a round piece of thicker cartilage that helps stabilize the shoulder.

Damage to the articular cartilage affects the ability of the shoulder to move smoothly and support movement. This can result in stiffness of the joint as well as pain if the cartilage wears down to the underlying bone and creates bone-on-bone friction. Damage across most of the articular cartilage occurs with osteoarthritis, but cartilage damage that primarily occurs in 1 location is called an osteochondral defect, or cartilage defect.

While this type of cartilage injury is most common in weight-bearing joints like the hip, knee, and ankle, it can also occur in the shoulder joint from injury or repeated stress. Shoulder cartilage defects are most often seen in younger athletic populations but can also occur in older adults from wear and tear over time.

Cartilage defect injuries most commonly result from a traumatic injury, such as a shoulder dislocation, but also occur with other shoulder conditions. These include avascular necrosis, where bone damage occurs due to a lack of blood supply; rotator cuff arthropathy, where shoulder osteoarthritis develops because of a significant rotator cuff tear; and osteochondritis dissecans, where poor blood causes cartilage and bone to separate and loosen within a joint.

These conditions reduce the stability of the shoulder and can lead to increased friction within the joint that can damage the articular cartilage. Chronic shoulder instability, often resulting from 1 or more shoulder dislocations, is a common source of repeated stress that breaks down a portion of the articular cartilage over time and increases the risk of developing shoulder osteoarthritis.

A health care provider will diagnose a shoulder cartilage defect starting with a physical examination and a history of a patient’s symptoms. Cartilage defects of the shoulder can produce a variety of different symptoms, including deep pain within the shoulder joint, general achiness that gets worse with arm movement, instability, limited range of motion, and grating or grinding within the shoulder joint.

There may also be the feeling that there is something stuck inside the shoulder causing irritation. This is referred to as a loose body, which is a piece of cartilage or bone that has broken off within the joint. A physical examination will include an observation of the patient’s arm movement, recreation of the positions that cause symptoms, and passive range of motion of the shoulder.

To help make a diagnosis, a health care provider will likely perform imaging studies. X-rays are used to examine the anatomy and alignment of the shoulder joint, while an MRI is used to examine the cartilage for injuries. A health care provider will use these findings along with a patient’s symptoms to recommend the appropriate treatment options.