Reverse shoulder replacement is a surgical procedure that is used to treat severe shoulder joint damage and dysfunction, particularly in cases where traditional shoulder replacement surgery is not suitable. In this procedure, the positions of the ball and socket in the shoulder joint are reversed, hence the name "reverse" shoulder replacement.
To understand reverse shoulder replacement, it is important to first grasp the anatomy and function of the shoulder joint. The shoulder joint is a complex structure that consists of a ball-shaped end of the upper arm bone (humerus) and a shallow socket in the shoulder blade (scapula). The joint is surrounded by muscles, tendons, ligaments, and a protective capsule. The rotator cuff, a group of four muscles and their tendons, plays a crucial role in shoulder stability and movement.
In a healthy shoulder, the rotator cuff muscles work together with the deltoid muscle to create a balance, allowing for smooth and painless arm movement. However, in certain cases, such as massive rotator cuff tears, advanced arthritis, or irreparable rotator cuff damage, the traditional shoulder replacement may not be effective due to the absence of intact tendons to support the prosthetic joint. This is where reverse shoulder replacement comes into play.
During a reverse shoulder replacement surgery, the surgeon makes an incision over the shoulder joint to access the damaged area. The humerus bone is prepared by removing the damaged ball-shaped head. Then, a metal ball component is attached to the end of the humerus bone. The socket portion of the shoulder joint, which is normally part of the scapula, is replaced with a plastic socket that contains a metal stem.
The positioning of the ball and socket is reversed in this procedure. The metal ball is placed on the scapula side, while the plastic socket is attached to the humerus bone. This configuration allows the deltoid muscle to take over the function of the damaged or absent rotator cuff tendons, providing stability and control to the joint.
The reverse shoulder replacement design changes the mechanics of the shoulder joint, allowing the deltoid muscle to compensate for the loss of rotator cuff function. The reversed ball-and-socket joint enables the deltoid muscle to power the arm movement, rather than relying on the damaged or absent rotator cuff tendons. This alteration in the joint mechanics can significantly improve the patient's ability to lift and rotate their arm, enhancing overall shoulder function and reducing pain.
After the components of the reverse shoulder replacement are securely in place, the incision is closed, and the patient is monitored during the recovery period. Physical therapy is an essential part of the rehabilitation process following surgery. The therapist will guide the patient through exercises and movements to gradually restore strength, range of motion, and stability to the shoulder joint.
As with any surgical procedure, there are potential risks and complications associated with reverse shoulder replacement. These can include infection, blood clots, nerve injury, shoulder instability, dislocation, implant loosening, and prolonged rehabilitation. It is important for patients to discuss the potential benefits and risks with their orthopaedic surgeon and understand the individualised considerations for their specific case.