Rough surfaces cause friction to develop when the joint moves. This friction causes pain from mechanical abrasion.
When cartilage erodes, weight is not evenly distributed across the joint surface. Bone on bone contact causes painful areas of stress concentration. This stress concentration can cause the neighboring bone to fracture and form potholes in the joint surface.
Stress concentration in the bone leads to the formation of osteophytes (bone spurs) around the joint. These spurs may limit motion by causing a mechanical block.
Cartilage breakdown causes inflammation in the joint fluid and joint lining. This can cause stiffness and swelling that worsens the mechanical pain.
What causes shoulder arthritis?
While not as common as rotator cuff disease, shoulder arthritis is among the most prevalent causes of shoulder pain and loss of function. Arthritis of the shoulder joint is less common than arthritis of the hip or knee. Individuals with arthritis in one joint are more likely to get it in another joint. While the exact cause of arthritis is not always known, researchers have identified certain risk factors that may predispose one to arthritis.
Age: Arthritis typically affects people in their 60s and 70s, though some people may develop severe joint degeneration as early as their 40s depending on the cause.
Overuse: There is general consensus that too much stress on the joint may accelerate cartilage wear. If the rate of breakdown exceeds the rate of healing then progressive wear of the joint surface will occur. The rate at which overuse can cause cartilage breakdown depends on a person’s healing capacity and the type of stress applied to the joint. Repetitive impact and vibratory forces are thought to predispose to joint wear.
Injury: Damage to the joint surface from fractures, dislocations or ligament injuries may disrupt the smooth cartilage surface. Depending on the severity of injury, these changes may be irreversible.
Prior Surgery: Certain types of surgery for shoulder instability have historically been associated with a higher risk of eventual shoulder arthritis. These procedures are rarely performed anymore.
Genetics: Arthritis can run in families. This is especially true of rheumatoid arthritis but can also be the case for osteoarthritis. When the predisposition for arthritis is inherited, people are often affected at a younger age and in multiple locations.
What are the different types of shoulder arthritis?
Over 100 different types of arthritis have been described but most of them are quite rare. The majority of cases of shoulder arthritis stem from only a handful of diagnoses.
Osteoarthritis: Accounting for more than 90% of cases, this is the most common form of arthritis and is generally thought to result from accumulated joint damage through wear and tear. The average age of onset is in the mid‑60s.
Rheumatoid Arthritis: This is an inflammatory arthritis caused by an abnormal immune system response against the body’s joints. Severe inflammation in the joint lining causes cartilage breakdown. It accounts for less than 10% of cases of shoulder arthritis and typically affects people in their early 50s (usually women).
Avascular Necrosis: This type of arthritis results when the bone beneath areas of the cartilage surface dies due to lack of blood supply. When the cartilage loses its foundation, it undergoes progressive degeneration. There are many causes of avascular necrosis, though in the majority of cases, the cause is unknown.
Post‑Capsulorraphy Arthritis: This arthritis develops years after a previous surgery to prevent recurrent shoulder dislocations. It results from restricting the ability to turn the arm out to the side. Most of the procedures that cause this type of arthritis are seldom performed today but were common in the 1970s and 80s.
Post‑Traumatic Arthritis: This type of arthritis occurs as a result of injury to or fracture of the shoulder joint. Disruption of the cartilage surface or abnormal bony alignment caused by fracture can lead to joint destruction over time.
Septic Arthritis: Arthritis may occur after an infection inside of the joint. These infections are uncommon but may occur when an infection spreads from elsewhere in the body.
Shoulder arthritis must be distinguished from rotator cuff disease, rotator cuff tear arthropathy, frozen shoulder, and neck arthritis, each of which may produce similar symptoms. Rotator cuff tears usually cause pain and weakness, but stiffness is less common. Frozen shoulder is characterized by shoulder stiffness, but the X‑rays are usually normal. Neck arthritis may cause shoulder pain and weakness that is worse when the head is held in certain positions.
What are the symptoms of shoulder arthritis?
Shoulder arthritis typically presents with slowly progressive pain and stiffness. Early on, the pain is usually activity related, but as the joint degeneration becomes more advanced, people may experience pain at rest and pain at night that awakens them from sleep. Roughness of the joint surfaces produces grating and grinding of the bones. Inflammation in the joint lining and pain both result in loss of motion. Progressive stiffness eventually limits shoulder function and thereby may cause muscle weakness and atrophy from disuse. A vicious cycle develops where pain leads avoidance of motion which leads to increased muscle tightness which leads to stiffness which leads to further pain and so on.
How is shoulder arthritis diagnosed?
Dr. Mullen diagnoses shoulder arthritis by reviewing the patient’s history, performing a thorough physical examination of the joint and taking the proper X‑rays. The examination of an arthritic shoulder reveals stiffness and roughness of the joint.
X‑rays of the shoulder reveal the contour of the joint surfaces and the status of the cartilage space between them. X‑rays of an arthritic shoulder usually show a narrowing of the space between the ball and socket–often to the point that bone is touching bone. These findings indicate that the normal cartilage has been destroyed. X‑rays do not show the soft tissues, such as scar tissue, that may also be limiting joint motion.
What can I do to keep it from getting worse?
The natural history of arthritis is one of progressive joint destruction. Currently there is no cure and cartilage degeneration does not heal or reverse itself. The rate at which joint degeneration occurs varies according to many different factors and cannot be predicted in any one case. In the early stages of arthritis, physical therapy is aimed at slowing down the wear process and improving comfort, motion and function. The following regimen should be considered not only as a first line of treatment, but also as a maintenance program for joint health.
Active rest: Avoiding activities that worsen symptoms, such as physical labor, is important. Pain and soreness are the body’s protective mechanism against deterioration and ignoring these symptoms or trying to work through them will likely only lead to increasing pain. By the same token, inactivity will lead to muscle atrophy and stiffness. Thus, low level activity that can be performed comfortably is recommended.
Stretching: Preventing stiffness is essential to a healthy shoulder. A daily, balanced flexibility program preserves motion and will improve comfort. Mobility keeps the tendons, ligaments and muscles about the shoulder robust.
Strengthening: Exercises that build strength and endurance without putting excessive stress on the joint also maintain joint health. When the cartilage is damaged, the muscles and tendons around the shoulder girdle must be kept in shape to further protect the joint surface. Exercises that simultaneously promote mobility and conditioning are recommended. These include: swimming, rowing, and upper body ergometer. Gentle rotator cuff strengthening exercises with rubber tubing or lightweight dumbbells and strengthening of the muscles around the shoulder blade should be performed as a maintenance program.
Aerobic conditioning: Dr. Mullen strongly encourages people with arthritis to maintain an active and healthy lifestyle. This includes weight control and cardiovascular conditioning. Walking programs, exercise bike, swimming and similar exercises are not only essential to joint health but also have a positive effect in terms of one’s general physical and mental health status.
Nutrition: Although no specific vitamin or minerals have been statistically shown to slow cartilage breakdown or rebuild damaged joints, a healthy, balanced diet is important in addressing the effects that arthritis can have on other body systems.
Glucosamine and chondroitin sulfate supplements may improve the symptoms of arthritis, especially in the early phases, and may be considered for maintenance joint health. Currently, there is conflicting scientific evidence supporting a beneficial effect in terms of pain relief. If symptoms have not changed after 8 weeks of use, however, these supplements are not likely to work.
What other treatments are available for shoulder arthritis?
Since we do not fully understand all of the factors that cause arthritis, many of our treatments are aimed at addressing the effects or the symptoms. In addition to a joint health program as outlined above, the following may be considered if shoulder arthritis becomes disabling.
Non‑steroidal anti‑inflammatory medications (NSAIDS): These include Ibuprofen, Motrin, Advil, Naprosyn, Aleve, Celebrex, and others. NSAIDS relieve pain and inflammation in the arthritic joint. They tend to be more effective in the earlier stages of the disease. Once severe degeneration occurs, pain derived from the mechanical abrasion of raw joint surfaces tends not to respond as reliably. These medications should be taken with food and should be used cautiously in anyone with a history of stomach ulcers.
Cortisone injections: Cortisone is a powerful anti‑inflammatory that can be inserted directly into the arthritic joint. It is often quite effective at minimizing symptoms. The effect may last anywhere from days to months and it is impossible to predict how long the injection will last. Injections should be used sparingly because repeated exposure to cortisone may eventually weaken the cartilage, underlying bone and tendons around the joint. We generally recommend no more than 3 injections with a minimum of 3 months between each.
Alternative medicine treatment: many forms of alternative medicine may ease symptoms and improve one’s outlook when faced with a chronic condition. These include yoga, tai chi, acupuncture, biofeedback, visualization, herbal supplements and others. It is important to recognize that, like most other treatments for arthritis, these modalities have not been shown to prevent or reverse arthritis. Nevertheless, when effective, they are an excellent adjunct to other standard treatments.
What surgical treatments are available for shoulder arthritis?
Arthroscopic debridement and manipulation under anesthesia: This technique may be used in cases of early arthritis before severe joint degeneration has occurred. The goal of this procedure is to use a camera and small incisions to remove any loose bodies from the joint, excise the inflamed joint lining and remove any scar tissue that limits shoulder motion. Bone spurs that block motion may also be removed. Following this part of the procedure, the arm is taken through a full range of motion to restore flexibility. Recovery from this procedure involves an immediate range of motion program. Progressive strengthening exercises are added along with aerobic conditioning. This procedure does not cure the arthritis but is designed to improve shoulder comfort and function during the early stages and hopefully delay the need for larger reconstructive procedures.
Shoulder replacement surgery: This is the most common surgical option. The goal of this procedure is to remove bone‑on‑bone roughness by using artificial components to replace the ball and socket. There are many variations of shoulder replacement surgery depending on whether or not the socket is resurfaced and what is used to resurface it. In general the humeral head (ball) is replaced with a round metal prosthesis. In a total shoulder replacement, the socket is replaced with a plastic component. In some instances it may not be beneficial to replace the socket. This is often the case in young patients and those who wish to remain very physically active. In these cases, the socket it often refinished to smooth and reorient its surface, but is not replaced. Shoulder replacement surgery is a highly successful procedure by may take 6 months or more to achieve a full recovery.
Shoulder fusion: this procedure involves surgically fusing the ball to the socket to prevent any motion between the surfaces. This technique, though successful in terms of pain relief, is seldom used as a first line treatment because it severely restricts range of motion. Shoulder fusion is generally a last resort when previous surgical treatments have failed and is rarely performed anymore.
What are the Indications for Surgery?
Surgery is indicated primarily for pain that interferes with a patient’s quality of life. If you can still get by with everyday activities and tolerate or manage the pain with conservative measures, then non‑operative treatment is preferred. When these treatments fail, surgery is usually the next step.
Surgery is most successful when patients are otherwise in good health or have other medical conditions which are stable and being appropriately managed. In addition, patients should be motivated to succeed as this motivation is critical to the postoperative recovery. Because recovery involves extensive rehabilitation, patients must be mentally and physically ready to commit the time and effort to the process.