Rheumatoid arthritis is an autoimmune disease in which immune system cells and chemicals mistakenly attack healthy joints in the body. The shoulder is often affected by this condition, causing pain and decreased function. Most commonly, shoulder involvement with rheumatoid arthritis affects both shoulders, although one may be worse than the other. Conservative and surgical interventions are used to treat rheumatoid arthritis in the shoulder.
Anatomy
The shoulder is a ball-and-socket joint formed by the upper arm bone and the shoulder blade. It is the most mobile joint in the body. The rotator cuff muscles stabilize the shoulder joint, keeping it in the socket as the arm moves. These muscles are located on the shoulder blade and tendons attach them to the upper arm bone. The rotator cuff tendons and cartilage lining the shoulder joint normally keep the bones in the shoulder from rubbing against one other during arm movement.
Rheumatoid arthritis attacks all the tissues in the shoulder joint. It frequently causes breakdown in the cartilage in the shoulder joint and the bones may eventually rub against each other. The ball of the shoulder joint can erode, causing divots in the surface of the bone. Tears often develop in the tendons of the shoulder, and muscles can shrink in size.
Diagnostic Imaging
Rheumatoid arthritis affects the position of the ball in the socket and erodes the shoulder joint surfaces. X-rays are taken in multiple positions to view the shoulder joint and assess for these changes.
Rotator cuff tendon injuries are common with rheumatoid arthritis. Ultrasound, MRI and CT scans are used to view these tendons to assess for inflammation, swelling and tears. Joint erosion is better visualized with these tests as well. Imaging tests tend to show only late-stage changes in the shoulder due to rheumatoid arthritis.
Treatment
Pain and inflammation from rheumatoid arthritis are often treated with over-the-counter and prescription nonsteroidal antiinflammatory medication – NSAIDs – such as ibuprofen (Advil, Motrin), aspirin (Bayer, Bufferin) and naproxen (Aleve, Anaprox, Naprelan, Naprosyn).
Disease modifying antirheumatic drugs – DMARDs – such as tocilizumab (Actrema) and methotrexate (Rheumatrex, Trexall) are also prescribed to slow the progression of the disease. These medications suppress the immune system to slow its attack on joint tissue. Cortisone injections are often given in the shoulder joint to decrease inflammation, swelling and pain.
Physical therapy treatments use heat, ultrasound and electrical stimulation to decrease pain and increase blood flow in the shoulder joint. Range of motion exercises are prescribed to improve movement and make daily tasks easier. Manual stretching is performed by the therapist to improve joint flexibility. Rotator cuff strengthening exercises are used to improve stability of the shoulder joint. This improves a person’s ability to perform daily tasks such as dressing, showering, reaching overhead, driving and carrying objects.
Surgery
Surgery is sometimes required to treat shoulder pain and functional limitations from rheumatoid arthritis. Hemiarthroplasty, total shoulder and reverse total shoulder arthroplasty are commonly performed to treat this condition, based on the structures that are damaged. Physical therapy is used to improve movement and function after each of these surgeries.
Hemiarthroplasty replaces the ball part of the shoulder joint with a prosthetic implant. This surgery is chosen when there is sufficient cartilage in the socket of the joint. Rotator cuff repair is often performed with this procedure to fix torn tendons.
Total shoulder arthroplasty replaces the ball and the socket with metal implants, eliminating the damaged joint surfaces completely. Rotator cuff repair is often necessary with this procedure as well. In addition to pain relief, the goal of this procedure is to improve the patient’s ability to elevate the arm. This improves daily tasks such as dressing, showering and putting dishes in the cupboard.
Reverse total shoulder arthroplasty switches the two surfaces in the shoulder joint. The socket component is attached to the upper arm, while the ball is attached to the shoulder blade in place of the original socket. This procedure is used for patients with rotator cuff tendon tears that cannot be fixed.