Rotator Cuff Arthropathy

A rotator cuff tear arthropathy is a condition that occurs when there is severe shoulder arthritis in the setting of a large rotator cuff tear. In order to be considered a rotator cuff tear arthropathy, there are three clinical findings that are present:

1. Insufficient function of the rotator cuff (typically a large tear)
2. Arthritis of the ball-and-socket (glenohumeral) joint
3. Shifting of the normal position of the ball within the socket (superior migration)

Rotator Cuff Function

The rotator cuff is the group of four muscles and tendons that surround the ball-and-socket shoulder joint. These muscles serve several important functions such as motion and strength of the shoulder. Another critical function of the rotator cuff is to provide a compressive force that holds the ball within the socket of the shoulder.

When the rotator cuff is not functioning properly, the mechanics of the shoulder joint can be altered.  Much like having your car wheels out of alignment can cause abnormal wear of the tires, having the rotator cuff damaged can cause the ball-and-socket of the shoulder to have altered alignment. Once the alignment is shifted (the humeral head, or ball of the ball-and-socket joint, shifts upward), the shoulder joint tends to wear out unevenly. This wearing out of the cartilage leads to the loss of the normal smooth cartilage lining of the joint.

Signs of a Rotator Cuff Tear Arthropathy

The signs of this condition are similar to normal shoulder arthritis, but there is often more weakness of the shoulder. Symptoms include:

• Shoulder pain
• Loss of mobility
• Weakness of the shoulder joint
• Swelling around the shoulder
• Atrophy of the musculature around the shoulder

Treatment of Cuff Tear Arthropathy

A rotator cuff tear arthropathy can create a challenging treatment problem. While shoulder replacements are effective treatment for shoulder arthritis, the standard implants rely on the rotator cuff to function properly. Just as the normal shoulder relies on proper functioning of the rotator cuff, a standard shoulder replacement also relies on this function of the rotator cuff. When the rotator cuff is not working, and a standard shoulder replacement is performed, the joint is abnormally aligned, and the socket portion of the replacement tends to loosen and wear out quickly.

When a rotator cuff tear arthropathy exists, a special type of implant is often used for treatment. One type of implant created for rotator cuff tear arthropathy is called a reverse shoulder replacement. This type of implant is designed to place a ball within the socket of the shoulder, and forms a new socket on the top of the arm bone (the humerus). This design alters the mechanics of the shoulder joint, such that it is not necessary to have a functioning rotator cuff.

_Sources

_{Ecklund KJ, Lee TQ, Tibone J, Gupta R. “Rotator Cuff Tear Arthropathy” J Am Acad Orthop Surg. 2007 Jun;15(6):340-9.}