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 makes 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. Learn more about Shoulder Anatomy
Several conditions can cause shoulder pain and disability, and lead patients to consider shoulder joint replacement surgery.
CLICK A HEADING TO LEARN MORE ABOUT EACH Condition.
This is an age-related "wear and tear" type of arthritis. It usually occurs in people 50 years of age and older, but may occur in younger people, too. 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. Unfortunately, there is no way to prevent the development of osteoarthritis. It is a common reason people have shoulder replacement surgery.
This is a disease in which the synovial membrane that surrounds the joint becomes inflamed and thickened. This chronic inflammation can damage the cartilage and eventually cause cartilage loss, pain, and stiffness. Rheumatoid arthritis is the most common form of a group of disorders termed "inflammatory 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. This causes shoulder pain and limits shoulder function.
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 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.
A severe fracture of the shoulder is another 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, a surgeon may recommend a shoulder replacement. Older patients with osteoporosis are most at risk for severe shoulder fractures.
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.
Every year, thousands of conventional total shoulder replacements are successfully done in the United States for patients with shoulder arthritis. This type of surgery, however, is not as beneficial for patients with large rotator cuff tears who have developed a complex type of shoulder arthritis called "cuff tear arthropathy." For these patients, conventional total shoulder replacement may result in pain and limited motion, and reverse total shoulder replacement may be an option.
Although shoulder joint replacement is less common than knee or hip replacement, it is just as successful in relieving joint pain.
Shoulder replacement surgery was first performed in the United States in the 1950s to treat severe shoulder fractures. Over the years, shoulder joint replacement has come to be used for many other painful conditions of the shoulder, such as different forms of arthritis.
In shoulder 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).
Today, about 53,000 people in the U.S. have shoulder replacement surgery each year, according to the Agency for Healthcare Research and Quality. This compares to more than 900,000 Americans a year who have knee and hip replacement surgery.
If nonsurgical treatments like medications and activity changes are no longer helpful for relieving pain, you may want to consider shoulder joint replacement surgery. Joint replacement surgery is a safe and effective procedure to relieve pain and help you resume everyday activities.
Whether you have just begun exploring treatment options or have already decided to have shoulder joint replacement surgery, this article will help you understand more about this valuable procedure.
A conventional shoulder replacement device mimics the normal anatomy of the shoulder: a plastic "cup" is fitted into the shoulder socket (glenoid), and a metal "ball" is attached to the top of the upper arm bone (humerus).
In a reverse total shoulder replacement, the socket and metal ball are switched. The metal ball is fixed to the socket and the plastic cup is fixed to the upper end of the humerus.
In a healthy shoulder, the "ball" of the humerus is held in the shoulder socket by several muscles and tendons, including the rotator cuff tendon.
A reverse total shoulder replacement works better for people with cuff tear arthropathy because it relies on different muscles to move the arm. In a healthy shoulder, the rotator cuff muscles help position and power the arm during range of motion.
A conventional replacement device also uses the rotator cuff muscles to function properly. In a patient with a large rotator cuff tear and cuff tear arthropathy, these muscles no longer function.
The reverse total shoulder replacement relies on the deltoid muscle, instead of the rotator cuff, to power and position the arm.
This procedure is most often used for patients who have had a failed total shoulder replacement. It is also helpful for patients who have had a complete tear of the rotator cuff, especially those whose injuries have led to an arthritic condition called cuff tear arthropathy.