Shoulder Anatomy
Your shoulder is made up of three bones: your upper arm bone (humerus), your shoulder blade (scapula), and your collarbone (clavicle). The shoulder is a ball-and-socket joint. The ball, or head, of your upper arm bone fits into a shallow socket in your shoulder blade. This socket is called the glenoid.

The surfaces of the bones where they touch are covered with articular cartilage, a smooth substance that protects the bones and enables them to move easily. A thin, smooth tissue called synovial membrane covers all remaining surfaces inside the shoulder joint. In a healthy shoulder, this membrane releases a small amount of fluid that lubricates the cartilage and eliminates almost any friction in your shoulder.

The muscles and tendons that surround the shoulder provide stability and support.

All of these structures allow the shoulder to rotate through a greater range of motion than any other joint in the body.

Shoulder Joint Replacement
In shoulder joint replacement surgery, the damaged parts of the shoulder are removed and replaced with artificial components, called a prosthesis. The treatment options are either replacement of just the head of the humerus bone (ball), or replacement of both the ball and the socket (glenoid).

Several conditions can cause shoulder pain and disability, and lead patients to consider shoulder joint replacement surgery.

Osteoarthritis (Degenerative Joint Disease)
This age-related “wear and tear” type of arthritis usually occurs in people over age 50 years, but occasionally in younger individuals. The cartilage that cushions the bones of the shoulder softens and wears away. The bones then rub against one another. Over time, the shoulder joint slowly becomes stiff and painful.

Rheumatoid Arthritis
This is a disease in which the synovial membrane that surrounds the joint becomes inflamed and thickened. This chronic inflammation eventually causes cartilage loss, pain, and stiffness.

Post-traumatic Arthritis
This can follow a serious shoulder injury. Fractures of the bones that make up the shoulder or tears of the shoulder tendons or ligaments may damage the articular cartilage over time, causing shoulder pain and limiting shoulder function.

Rotator Cuff Tear Arthropathy
A patient with a very large, long-standing rotator cuff tear may develop cuff tear arthropathy. In this condition, the changes in the shoulder joint due to the rotator cuff tear may lead to arthritis and destruction of the joint cartilage.

Avascular Necrosis (Osteonecrosis)
Avascular necrosis is a painful condition that occurs when the blood supply to the bone is disrupted. Because bone cells die without a blood supply, osteonecrosis can ultimately cause destruction of the shoulder joint and lead to arthritis. Chronic steroid use, deep sea diving, severe fracture of the shoulder, sickle cell disease, and heavy alcohol use are risk factors for avascular necrosis.

Severe Fractures
A severe fracture of the shoulder is a common reason people have shoulder replacements. When the head of the upper arm bone is shattered, it may be very difficult for a doctor to put the pieces of bone back in place. In addition, the blood supply to the bone pieces can be interrupted. In this case, an orthopedic surgeon may recommend a shoulder replacement. Failed Previous Shoulder Replacement Surgery
Although uncommon, some shoulder replacements fail, most often because of implant loosening, wear, infection, and dislocation. When this occurs, a second joint replacement surgery — called a revision surgery — may be necessary.

People who benefit from surgery often have:
• Severe shoulder pain that interferes with everyday activities.
• Moderate to severe pain that prevents a good night’s sleep.
• Loss of motion and/or weakness in the shoulder.
• Failure to substantially improve with other treatments such as anti-inflammatory medications, cortisone injections, minimally invasive surgery or physical therapy.

Orthopaedic Evaluation
An evaluation with an orthopedic surgeon consists of several components, including:
• A medical history.
• A physical examination.
• Blood tests.
• X-rays.
• Magnetic Resonance Imaging (MRI)

Your orthopedic surgeon will review the results of your evaluation with you and discuss whether shoulder joint replacement is the best method to relieve your pain and improve your function. Other treatment options — including medications, injections, physical therapy or minimally invasive surgery— will also be discussed and considered.

There are different types of shoulder replacements. Your orthopedic surgeon will evaluate your situation carefully and discuss with you which type of replacement would best meet your health needs. Do not hesitate to ask what type of implant will be used in your situation, and why that choice is right for you.

Many thousands of patients have experienced an improved quality of life after shoulder joint replacement surgery. They experience less pain, improved motion and strength, and better function.