Shoulder Replacement

Although less common than a knee or hip replacement, shoulder joint replacement typically provides the same benefits of joint replacement including reduction of pain and restoration of more normal joint movement. For some, shoulder replacement provides a significant improvement in their ability to participate in the activities of daily living comfortably. With that said, however, deciding to replace the shoulder joint should be a carefully considered decision weighing all the benefits, risks and complications.

Two components make up the artificial shoulder joint. One is the humeral component, which replaces the head of the upper arm bone. It is made of metal (usually cobalt/chromium-based alloys) and has a rounded ball attached to a stem that fits into your bone. The second component, the glenoid component, replaces the socket. This portion of the joint is most commonly constructed from plastic. Either (a hemiarthroplasty, humeral head replacement) or both of the components may by replaced (total shoulder replacement). The components come in various sizes and shapes and are held in place with either acrylic bone cement (cemented) or bone ingrowth (cementless). As in the natural joint, the surrounding muscles and tendons provide stability for the prosthesis.

The surgical incision is 3″ to 4″ long and is made on the front of the shoulder from the collarbone (clavicle) to the point where the shoulder muscle (deltoid) attaches to the upper arm bone. Special attention will be paid to all the structures that cross the shoulder, including the vessels and nerves and the muscles will be carefully inspected to look for injury.

The upper arm bone is dislocated from the socket to expose the ball-like end of the upper arm. Only the portion of the bone covered by articular cartilage is removed. The cavity of the upper arm bone is cleaned and enlarged to facilitate the insertion of the humeral component of the replacement’s stem, with the proper size and shape particular to the patient selected. The top end of the bone is smoothed so the stem can be inserted flush with the bone surface.

Depending on the health of the socket and the surrounding muscles the socket may or may not be replaced. However, if the socket is beyond salvage, the surgeon will implant the glenoid component. The damaged cartilage is removed the new socket is contoured to overlie the existing socket. Protrusions on the polyethylene component are then fitted into holes drilled in the socket surface. Once a precise fit is achieved, the component is cemented into position. The arm bone, with its new prosthetic head, is replaced in the socket. The surgeon reattaches the supporting tendons and closes the incision. The arm is placed in a sling and a support pillow is placed under the elbow to protect the repair. A drainage tube is used to remove excess fluids and is usually removed on the day after surgery.

Rehabilitation after should joint replacement surgery usually begins the same day as the surgery. Compliance with a rehabilitation program is vital to the success of the replacement. Initial physical therapy will begin in the hospital with passive-assisted range of motion exercises followed by the use of pulleys at home to bend and extend the arm.

There are important do’s and don’t after shoulder joint replacement once the patient returns home:

• Don’t overdo it! After the first six weeks of surgery, the patient should not lift anything heavier than a cup of coffee.
• Ask for assistance. Please inquire about services that are available, such as home support.
• Wear the sling at night while sleeping every night for at least one month after surgery.
• Do not use your arm to push up from a chair or in bed.
• Carefully follow the prescribed exercise plan, sometimes doing the exercises 5-6 a day.
• Don’t participate in any sports activities or heavy lifting for at least six months.

Complications after shoulder replacement surgery occur less frequently than with other joint replacement surgeries. However, there are risks. Infection, intraoperative fracture of the upper arm bone or postoperative fractures, postoperative instability and loosening of the glenoid component are the most common complications. Advances in surgical techniques and prosthetic innovations are helping to reduce the occurrence of complications.