Shoulder Replacement
The shoulder is the most mobile joint in the human body, with a complex arrangement of structures working together to provide the necessary movement. The shoulder is a ball-and-socket joint made up of three bones: the humerus (the bone in the upper arm), the scapula (the shoulder blade), and the clavicle (the collarbone). A strong network of soft tissues and bones work cohesively to provide movement and stability to the shoulder. The head of the humerus fits into a shallow socket in the scapula with the shoulder capsule, which is a strong connective tissue, surrounds the shoulder joint. Synovial fluid lubricates the joint and the shoulder capsule to ease the movement of the shoulder. This socket is called the glenoid and a combination of tendons and muscles, called the rotator cuff, center the humerus in the glenoid, which is the shoulder socket.
Overview
There are two joints in the shoulder, both of which can be affected by arthritis. The acromioclavicular joint (AC joint) is located where the clavicle meets the tip of the scapula. The glenohumeral joint is located where the head of the humerus fits into the scapula. There are many forms of arthritis with five major types that typically affect the glenohumeral joint:
Osteoarthritis - Osteoarthritis is the most common form of arthritis and occurs when the protective cartilage on the ends of your bones wears down over time. It’s often called a degenerative joint disease where the cartilage experiences a significant amount of wear and tear over a long period of time, generally occurring in individuals over the age of 50.
Rheumatoid Arthritis (RA) - Rheumatoid arthritis is quite possibly the most serious form of arthritis as it is a major crippling disorder. Unlike osteoarthritis, rheumatoid arthritis affects the synovial membrane (lining of the joints), causing a painful swelling, resulting in joint deformity and bone erosion. Rheumatoid arthritis is three to four times more likely to occur in women and may affect various systems of the body such as eyes, heart, lungs, skin, and the nervous system.
Post-Traumatic Arthritis - Traumatic arthritis is caused by a major or repeated trauma to the articular cartilage. This is most common among individuals who were/are athletic or active. Injuries to joints such as a fracture or dislocation can cause major damage to the articular cartilage, which leads to arthritic changes in the joint over time.
Avascular Necrosis - Avascular necrosis occurs when the blood supply to the head of the humerus is limited or disrupted due to an injury such as a dislocation or fracture. It can also be a complication from some medication. The lack of blood can cause the bone to breakdown and damage the articular cartilage, resulting in arthritis. This can also occur spontaneously without an injury.
Rotator Cuff Tear Arthopathy - Rotator cuff tear arthopathy is the development of arthritis as a result of a long-standing, large tear in the rotator cuff. When this occurs, the torn rotator cuff is no longer able to hold the head of the humerus in the glenoid socket, causing the ball to ride up, out of the socket. This can damage the surfaces of the bones and cause arthritis.
Symptoms
Individuals who are potential candidates of shoulder replacement surgery typically have the following symptoms:
- Pain that increases with activity and progressively gets worse
- Limited or restricted range of motion in the shoulder joint
- Pain that interferes with sleep, rest, and day-to-day activities
- Popping, grinding, or crunching in the shoulder
- A sense of stiffness in the shoulder
If conditions worsen or are persistent despite the use of medication and physical therapy, a visit to a physician is highly recommended to identify the cause of the pain and avoid further complications.
Diagnosis
Glenohumeral arthritis is diagnosed with a combination of patient history, physical examination and imaging studies. After discussing the individual's symptoms, the physician will examine the shoulder for weakness, tenderness, pain, and limitation of both passive and active range of motion. The physician will then order an X-ray to examine narrowing of the joint space, changes in the bones, or the formation of bone spurs, and confirm the diagnosis. In some cases, the physician may also order a CT scan or MRI scan to further evaluate the shoulder and rule out other shoulder joint conditions. Once a thorough analysis is done, the physician will discuss options to relieve pain and improve function of the shoulder joint.
Treatment
As with most arthritic conditions, the initial treatment will be more-conservative, non-operative treatment. If shoulder pain persists and the non-operative treatments have been exhausted, the physician may recommend an operative approach. Shoulder replacement surgery is extremely technical; therefore, the physician will evaluate the individual’s conditions and situation and provide recommendation for the best approach.
Total Shoulder Arthroplasty - Total shoulder arthroplasty, also known as total shoulder replacement, is performed when arthritis or degenerative shoulder joint disease makes the shoulder stiff and painful. Individuals with bone-on-bone arthritis are ideal candidates for this procedure. An incision is made in front of the arm. The tendons and muscles surrounding the shoulder joint are moved away to expose the glenoid and the humeral head and the shoulder is moved to provide easy access to the joint. The humeral head is then removed and the glenoid cavity is cleaned out in preparation for the replacement prosthesis. The hollow channel inside the humerus is prepared for the humeral stem to be inserted. The physician may then either use cement to secure the stem in the hollow channel or “press-fit” the stem into the channel. A carefully fitted ball is secured to the end of the stem and a plastic insert is attached to the glenoid cavity. The shoulder joint is then repositioned and all surrounding tissue is put back into place. The incision is closed and the procedure is completed.
Stemmed Hemiarthroplasty - Depending on the condition of the shoulder the physician may recommend a stemmed hemiarthroplasty, or partial shoulder replacement. For example, individuals who have severely fractured the head of the humerus, but have maintained a normal socket, are ideal candidates for this procedure. The surgical procedure is identical to that of a total shoulder replacement, however the glenoid cavity is left alone and the metal ball that is secured to the humeral stem is positioned into the normal glenoid cavity.
Resurfacing Hemiarthroplasty - Depending on the condition of the shoulder and the humerus, the physician may recommend a resurfacing hemiarthroplasty. Younger individuals who have no fresh fractures of the humeral head or neck and a normal glenoid cavity with healthy cartilage surface may be candidates for this procedure. A resurfacing hemiarthroplasty replaces just the joint surface of the humeral head with a cap-like man-made prosthesis. There is no need for a humeral stem in this procedure since there are no fractures. The advantage of this procedure is that it is a conservative way to preserve the original bone.
Reverse Total Shoulder Replacement - In some cases, the physician may recommend a reverse total shoulder replacement. Individuals who have completely torn their rotator cuff and have osteoarthritis and have severe arm weakness, patients with fractures, or those who have previously had a total shoulder replacement that has failed may be candidates for this procedure. In a reverse total shoulder replacement surgery, the socket and the metal ball are switched. The surgical process is identical to that of a total shoulder replacement, however, the socket is secured to the end of the humeral stem and a carefully fitted ball is placed in the glenoid cavity. In other words, the ball and socket joint becomes a socket and ball joint. This allows the individual to use their deltoid muscle instead of their rotator cuff to lift and rotate the arm.
Recovery
There will be pain after a shoulder replacement surgery. However, the physician will provide the necessary medication for managing pain. Regardless of the treatment approach taken, patients go through a rehabilitation program which includes physical therapy exercises that are crucial to restore range of motion. Home care with respect to wound care, diet and exercise will be critical for the first few weeks following surgery. Each patient is unique, so the therapy program will vary based on his/her level of pain, extent of injury, and desired level of activity they would like to return to. Recovery time after surgery depends on the complexity of the procedure, but the individual's commitment to following all the exercises prescribed by the physical therapist is the most important factor in returning to activities.
Disclaimer
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