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Osteoarthritis (OA), also known as arthrosis or degenerative joint disease, is a disease featuring pain and impaired function of the joints. It is the most common form of arthritis. While inflammation contributes to the disease process, the main cause is "wear and tear" to the synovium (joint lining). Treatment is with non-steroidal anti-inflammatory drugs (NSAIDs), local injections with glucocorticoids and with joint replacement surgery. There is no cure for osteoarthritis.
Signs and symptoms
The main symptoms are pain and restricted movement. The pain is chronic pain or gives varying amounts of discomfort when standing and walking. Pain is generally described as aching, sharp, or a burning sensation in the associated muscles and tendons, and includes loss of mobility and often stiffness. Humid weather increases the pain in many patients. Patients can experience muscle spasm and contractions in the tendons. Osteoarthritis can cause a crackling noise (called crepitus) when moved or palpated. Occasionally, affected joints may fill with fluid. Some develop Heberden's nodes and/or Bouchard's nodes in the fingers when these are affected.
Diagnosis
The joints mainly affected by osteoarthritis are the hip joints and the knee joints, although in theory any joint in the body can be affected. Osteoarthritis can affect the fingers, the spine, and the shoulder.
The diagnosis is made on the basis of the history, physical examination (restricted movement, crepitations) and X-rays of the joints. Occasionally, MRI (magnetic resonance imaging) may be required to examine the extent of the damage, especially in the spine. Imaging techniques can reveal damaged cartilage, loss of joint space, or bone spurs indicating the presence of osteoarthritis.
Pathophysiology
The crucial factor in the development of osteoarthritis is the disappearance of synovium and later all cartilage of affected joints. An inflammatory reaction, local resorption of bone and formation of osteophytes (bone processes) play a role. The patient experiences pain upon weight bearing, like walking and standing, as the bone surfaces are now unprotected by cartilage. Due to decreased movement (because of the pain), regional muscles may atrophy and ligaments may become more lax.
Osteoarthritis results from a combination of genetic predisposition and joint injuries. Contributing factors include congenital hip luxation (which is genetically determined), obesity, osteoporosis, and inflammatory diseases such as Perthes' disease and all chronic forms of arthritis (e.g. rheumatoid arthritis and gout).
As it progresses, joints appear larger, are stiff and painful and usually feel worse the more they are used throughout the day, which distinguishes it from rheumatoid arthritis.
Treatment
Mild cases are treated with nonsteroidal anti-inflammatory drugs (NSAIDs). These include acetaminophen (paracetamol) - which mainly reduces the pain - and agents such as diclofenac, ibuprofen and naproxen. High doses are often required. All NSAIDs act by inhibiting the formation of prostaglandins, which play a central role in inflammation and pain. Unfortunately, there is an increased risk of peptic ulceration with earlier NSAIDs. COX-2 selective inhibitors (such as valdecoxib, celecoxib, and the withdrawn rofecoxib) reduce this risk substantially.
Topical treatments are effective in treating pain associated with arthritis. Creams and lotions containing capsaicin are effective in relieving arthritic pain. They are especially useful for patients in whom NSAIDs are contraindicated, or where these cause intolerable side-effects.
Severe pain in specific joints can be treated with local injections with lidocaine (or similar local anaesthetics) and glucocorticoids (such as hydrocortisone). If the above management is ineffective, surgery (joint replacement) may be required. Individuals with very painful osteoarthritic joints may require surgery such as fragment removal, repositioning bones, or fusing bone to increase stability and reduce pain. For severe pain, narcotic pain relievers such as tramadol and eventually opioids (hydrocodone, oxycodone or morphine) may be necessary; this is reserved for very severe cases and is rarely necessary.
The substances glucosamine and chondroitin sulphate have recently been shown to improve symptoms of osteoarthritis. However, recent evidence shows that glucosamine is not effective in treating osteoarthritis of the knee (McAlindon et al 2004). Another nutritional supplement showing promise is S-adenosyl-methionine. Small scale studies have shown it to be as effective as NSAIDs in reducing pain although it takes about four weeks for the effect to take place.
Coping skills
Assistive devices may be useful in maintaining mobility. In the case of osteoarthritis of the knees, knee braces, a cane, or a walker can be a helpful aid for walking and support. Regular exercise, if possible, in the form of walking or swimming, is encouraged. Weight loss can delay progression. Cold or heat therapy benefits some patients, as do relaxation techniques.
Dealing with chronic pain can be difficult and result in depression. Communicating with others with osteoarthritis is helpful, as is maintaining a positive attitude. People who take control of their treatment, communicate with their doctor, and actively manage their arthritis experience less pain and function better.
Epidemiology
Osteoarthritis affects nearly 21 million people in the United States. Osteoarthritis accounts for 25% of visits to primary care physicians and half of all NSAID prescriptions; it is estimated that 80% of the population will have radiographic evidence of osteoarthritis by age 65, although only 60% of those will be symptomatic (Green 2001).
References
- Green GA. Understanding NSAIDS: from aspirin to COX-2. Clin Cornerstone 2001;3:50-59. PMID 11464731.
- McAlindon T, Formica M, LaValley M, Lehmer M, Kabbara K. Effectiveness of glucosamine for symptoms of knee osteoarthritis: Results from an internet-based randomized double-blind controlled trial. Am J Med 2004;117:643-9. PMID 15501201.
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