Shoulder Arthroplasty

Total Shoulder Replacement

The typical total shoulder replacement involves replacing the arthritic joint surfaces with a highly polished metal ball attached to a stem, and a plastic socket.

A total shoulder joint replacement.

These components come in various sizes. They may be either cemented or “press fit” into the bone. If the bone is of good quality, your surgeon may choose to use a non-cemented (press-fit) humeral component. If the bone is soft, the humeral component may be implanted with bone cement. In most cases, an all-plastic glenoid (socket) component is implanted with bone cement.

Implantation of a glenoid component is not advised if:

• The glenoid has good cartilage
• The glenoid bone is severely deficient
• The rotator cuff tendons are irreparably torn

Patients with bone-on-bone osteoarthritis and intact rotator cuff tendons are generally good candidates for conventional total shoulder replacement.

These x-rays were taken before and after total shoulder replacement surgery for osteoarthritis.

Stemmed Hemiarthroplasty

Depending on the condition of your shoulder, your surgeon may replace only the ball. This procedure is called a hemiarthroplasty. In a traditional hemiarthroplasty, the head of the humerus is replaced with a metal ball and stem, similar to the component used in a total shoulder replacement. This is called a stemmed hemiarthroplasty.

Some surgeons recommend hemiarthroplasty when the humeral head is severely fractured but the socket is normal. Other indications for a hemiarthroplasty include:

• Arthritis that only involves the head of the humerus with a glenoid that has a healthy and intact cartilage surface
• Shoulders with severely weakened bone in the glenoid
• Some shoulders with severely torn rotator cuff tendons and arthritis

Sometimes, surgeons make the decision between a total shoulder replacement and a hemiarthroplasty in the operating room at the time of the surgery.

Studies show that patients with osteoarthritis get better pain relief from total shoulder arthroplasty than from hemiarthroplasty.

Resurfacing Hemiarthroplasty

Resurfacing hemiarthroplasty involves replacing just the joint surface of the humeral head with a cap-like prosthesis without a stem. With its bone preserving advantage, it offers those with arthritis of the shoulder an alternative to the standard stemmed shoulder replacement.

Resurfacing hemiarthroplasty may be an option for you if:

• The glenoid still has an intact cartilage surface
• There has been no fresh fracture of the humeral neck or head
• There is a desire to preserve humeral bone

For patients who are young or very active, resurfacing hemiarthroplasty avoids the risks of component wear and loosening that may occur with conventional total shoulder replacements in this patient population. Due to its more conservative nature, resurfacing hemiarthroplasty may be easier to convert to total shoulder replacement, if necessary at a later time.

This x-ray shows the cap-like prosthesis used in resurfacing hemiarthroplasty.

Reverse Total Shoulder Replacement

Another type of shoulder replacement is called reverse total shoulder replacement. Reverse total shoulder replacement is used for people who have:

• Completely torn rotator cuffs with severe arm weakness
• The effects of severe arthritis and rotator cuff tearing (cuff tear arthropathy)
• Had a previous shoulder replacement that failed

An x-ray of a reverse total shoulder replacement.

For these individuals, a conventional total shoulder replacement can still leave them with pain. They may also be unable to lift their arm up past a 90-degree angle. Not being able to lift one’s arm away from the side can be severely debilitating.

In reverse total shoulder replacement, the socket and metal ball are switched. That means a metal ball is attached to the shoulder bone and a plastic socket is attached to the upper arm bone. This allows the patient to use the deltoid muscle instead of the torn rotator cuff to lift the arm.

(Left) Rotator cuff arthropathy. (Right) The reverse total shoulder replacement allows other muscles — such as the deltoid — to do the work of the damaged rotator cuff tendons.