While less common than knee or hip joint replacement, shoulder arthroplasty has been performed since the 1950s and can be an effective treatment to relieve pain and restore function to the shoulder.
The shoulder is a ball and socket joint and the connection point of three bones, the humerous (upper arm bone), the scapula (shoulder blade), and the clavicle (collarbone). When working properly, the connecting surfaces of these three bones are protected by articular cartilage, which allows for smooth movement within the joint. This friction-free movement is further supported by synovial fluid, a natural lubrication produced by the synovial membrane covering the remaining surfaces. When all components are healthy, the shoulder offers the greatest range of motion of any joint in the body.
Unfortunately, a number of conditions can impact the health and function of the shoulder, leading to pain, stiffness, and loss of function. These include:
- Osteoarthritis – “wear and tear” age-related degeneration that over time wears away the cartilage in the joint needed to protect the bones. Direct bone-on-bone friction results leading to pain and stiffness.
- Rheumatoid arthritis – a chronic condition that causes inflammation and thickening of the synovial membrane surrounding the bones of the joint. This inflammation damages the cartilage, eventually leading to cartilage loss, stiffness, and pain.
- Rotator cuff tear – the rotator cuff is comprised of four muscles surrounding the shoulder joint. A large tear can cause one or more of these muscles to contract and result in an abnormal alignment of the joint bones. This irregularity in turn can lead to “wear and tear” arthritis in the joint.
- Avascular Necrosis – disrupted blood supply to the bone leading to joint damage and arthritis.
- Bone fractures or tendon/ligament tears
The goal of shoulder treatment is to relieve pain and return function. When conservative treatments such as physical therapy or steroid injections do not result in long-lasting pain relief, shoulder replacement may be appropriate.
Shoulder arthroplasty involves surgically removing the damaged areas of the joint and replacing them with man-made implants, typically a metal ball and plastic socket. There are multiple types of shoulder replacement procedures to address varying conditions and your surgeon will explain the option that will best meet your needs. These options include:
- Total Shoulder Replacement (TSA) – TSA involves removing the humeral head of the upper arm bone and replacing with a metal ball implant. A plastic surface is attached to the concave portion of the shoulder blade called the glenoid fossa and provides the smooth “socket” surface of the new joint.
- Stemmed Hemiarthroplasty – Depending on the condition of the shoulder joint, the surgeon may elect to replace only the humeral head, or “ball” of the joint leaving the natural glenoid intact.
- Reverse Shoulder Replacement – A reverse shoulder replacement involves implanting both a new humeral head and socket but the location of the implants is reversed. The “socket” is implanted on the humerous (upper arm) bone and the “ball” is attached to the patient’s natural socket on the glenoid (shoulder) bone. Because this positioning transfers the job of powering and positioning the arm to the deltoid muscle, it is an option available when the soft tissues of the rotator cuff are too damaged to function.