What Is Osteoarthritis?
Osteoarthritis is the most common type of arthritis. People usually have joint pain and stiffness. Unlike rheumatoid arthritis, it does not affect skin tissue, the lungs, eyes, or blood vessels.
In osteoarthritis, cartilage—the hard, slippery tissue that protects the ends of bones where they meet to form a joint—wears away. The bones rub together, causing pain, swelling, and loss of motion. Over time, the joint also may lose its normal shape. Bone spurs—small deposits of bone—may grow on the edges of the joint. Also, bits of bone or cartilage can break off inside, causing more pain and damage.
Where does osteoarthritis occur?
Hands—Osteoarthritis of the hands seems to run in families. Women are more likely than men to have hand involvement. For most, it develops after menopause. Small, bony knobs may appear on the end joints (those closest to the nails) of the fingers. Fingers can become enlarged and gnarled, and may ache or be stiff and numb. The base of the thumb joint also is commonly affected.
Knees—Symptoms include stiffness, swelling, and pain. This makes it hard to walk, climb, and get in and out of chairs and bathtubs.
Hips—There is pain and stiffness of the joint itself. But sometimes pain is felt in the groin, inner thigh, buttocks, or even the knees. Osteoarthritis of the hip may limit moving and bending. This can make dressing or other daily activities a challenge.
Spine—There is stiffness and pain in the neck or lower back. In some cases, arthritis-related changes in the spine can put pressure on the nerves where they exit the spinal column. This results in weakness, tingling, or numbness of the arms and legs. In severe cases, bladder and bowel function can be affected.
Osteoarthritis Basics: The Joint and Its Parts
Joints allow movement between the bones and absorb the shock from walking or other repetitive motion. Joints are made up of:
Cartilage. A hard, slippery coating on the end of each bone.
Joint capsule. A tough membrane that encloses all the bones and other joint parts.
Synovium (sin-O-vee-um). A thin membrane inside the joint capsule that secretes synovial fluid.
Synovial fluid. A fluid that lubricates the joint and keeps the cartilage smooth and healthy.
Ligaments, tendons, and muscles. Tissues that surround the bones and joints, a llowing the joints to bend and move. Ligaments are tough, cord-like tissues that connect one bone to another. Tendons are tough fibers that connect muscles to bones. Muscles are bundles of specialized cells that, when stimulated by nerves, either relax or contract to produce movement.
A Healthy Joint
Illustration: National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
In a healthy joint, the ends of bones are encased in smooth cartilage. Together, they are protected by a joint capsule lined with a synovial membrane that produces synovial fluid. The capsule and fluid protect the cartilage, muscles, and connective tissues.
A Joint With Severe Arthritis
A Joint With Severe Osteoarthritis.
Illustration: National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
With osteoarthritis, the cartilage wears away. Spurs grow out from the edge of the bone, and synovial fluid increases. The joint feels stiff and sore.
- Osteoarthritis is the most common type of arthritis. More common in older people, it is sometimes called degenerative joint disease.
- Osteoarthritis most often occurs in the hands (at the ends of the fingers and thumbs), spine (neck and lower back), knees, and hips.
- Some 27 million Americans age 25 and older have osteoarthritis.
- Osteoarthritis is more likely in overweight people and among those with jobs that stress particular joints.
- Exercise is one of the best treatments for osteoarthritis.
- Before age 45, osteoarthritis is more common in men. After 45, it is more common in women.
Warning Signs of Osteoarthritis
- Pain and stiffness in a joint after getting out of bed or sitting for long.
- Swelling in one or more joints, especially those at the ends of the fingers (closest to the nail), thumbs, neck, lower back, knees, and hips.
- Crunching feeling or the sound of bone rubbing on bone
- Osteoarthritis may progress quickly, but in most people it develops gradually. It is relatively mild and interferes little with daily life in some people. Others have significant pain and disability.
- If you feel hot or your skin turns red, or if your joint pain is accompanied by a rash, fevers, or other symptoms, you probably do not have osteoarthritis. Check with your health provider about possible other causes, such as rheumatoid arthritis.
A combination of the following methods are used to diagnose osteoarthritis:
Clinical history—You will be asked when the condition started and how your symptoms have changed since. You will also describe any other medical problems you or your family may have, and any medications being taken. This helps your doctor make a diagnosis and understand the disease’s impact on you.
Physical examination—Your doctor checks your strength, reflexes, and general health. She or he also examines bothersome joints and observes your ability to walk, bend, and carry out daily activities, such as dressing.
X rays—X-rays will help determine the form of arthritis and how much damage there is, including cartilage loss, bone damage, and bone spurs.
Magnetic resonance imaging —Magnetic resonance imaging (MRI) provides high-resolution computerized images of internal body tissues. It is used if there is pain, X-rays don’t show much, or there is damage to other joint tissues.
Other tests—Your doctor may order blood tests to rule out other causes of symptoms. Fluid may also be drawn from the joint for microscopic examination to determine whether the pain is from a bacterial infection or uric acid crystals, indicating gout.
Doctors often combine treatments to fit a patient’s needs, lifestyle, and health. Osteoarthritis treatment has four main goals: Improve joint function, keep a healthy body weight, control pain, and achieve a healthy lifestyle. Treatment plans can involve:
Exercise—Research shows that exercise can improve mood and outlook, decrease pain, increase flexibility, strengthen the heart and improve blood flow, maintain weight, and promote general physical fitness. Your doctor and/or physical therapist can recommend the exercises best for you.
Weight control—Weight loss can reduce stress on weight-bearing joints, limit further injury, and increase mobility. A healthy diet and regular exercise help reduce weight. A dietitian can help you develop healthy eating habits.
Rest and relief from stress on joints—Learn to recognize the body’s signals, and know when to stop or slow down. Regularly scheduled rest prevents pain from overexertion. Proper sleep is important for managing arthritis pain. If you have trouble sleeping, relaxation techniques, stress reduction, and biofeedback can help.
Nondrug pain relief and alternative therapies—You may find relief from:
- Heat or cold (or a combination of both). Heat—with warm towels, hot packs, or warm bath or shower—can increase blood flow and ease pain and stiffness. Cold packs (bags of ice or frozen vegetables wrapped in a towel) can reduce inflammation, relieving pain or soreness.
- Massage uses light stroking and/or kneading of the muscles to increase blood flow and warm the stressed joint.
- Complementary and alternative therapies—Some people have found relief from such therapies as acupuncture. A large study supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and the National Center for Complementary and Alternative Medicine (NCCAM) showed that acupuncture can relieve pain and improve function in knee osteoarthritis.
- Nutritional supplements—such as glucosamine and chondroitin sulfate have been reported to improve osteoarthritis symptoms in some people.
When selecting medicines, your doctor will consider the intensity of pain, potential side effects of the medication, your medical history, and other medications you are taking. By working together, you and she or he can find the medication that best relieves your pain with the least risk of side effects.
The following medicines are commonly used to treat osteoarthritis:
Acetaminophen—A common over-the-counter pain reliever. It is often the first choice for osteoarthritis patients because of its safety and effectiveness compared to some other drugs.
NSAIDs (non-steroidal anti-inflammatory drugs)—A large class of medications for both pain and inflammation. It includes aspirin, ibuprofen, naproxen, and others. Some NSAIDs are available over the counter, while more than a dozen others are available only with a prescription. NSAIDs can have significant side effects. Anyone taking NSAIDs regularly should be monitored by a doctor.
Narcotic or central acting agents—Mild narcotic painkillers containing codeine or hydrocodone are often effective against osteoarthritis pain. But because of their potential for physical and psychological dependence, they are generally for short-term use.
Corticosteroids—Powerful anti-inflammatory hormones that may be injected into the affected joints for temporary relief. No more than four treatments per year are recommended.
Hyaluronic acid substitutes—These medications are injected to help lubricate and nourish joints. They are approved only for osteoarthritis of the knee.
Other medications—Doctors also may prescribe topical pain-relieving creams, rubs, and sprays, which are applied directly to the skin over painful joints. Because most medicines used to treat osteoarthritis have side effects, it is important to learn as much as possible about the medications you take, even the ones available without a prescription.
For many people, surgery helps relieve the pain and disability of osteoarthritis. You may have surgery to:
- remove loose pieces of bone and cartilage (arthroscopy)
- reposition bones (osteotomy)
- resurface bones (joint resurfacing).
Surgeons also may replace affected joints with artificial ones called prostheses. These can last up to 15 years or longer. The surgeon chooses the prosthesis according to the patient’s weight, sex, age, activity level, and other medical conditions.
After surgery and rehabilitation, the patient typically feels less pain and moves more easily.
No pills, yet . . .
“There are no pills yet for osteoarthritis, but we’re working on it,” says Linda Sandell, Ph.D., professor of Orthopaedic Surgery and of Cell Biology at the Washington University School of Medicine, in St. Louis. In osteoarthritis, the soft tissue called cartilage, which cushions the knees and other joints of the body, wears away, causing pain and loss of mobility.
“There are no pills yet for osteoarthritis, but we’re working on it . . . “
“It’s a huge and growing public health issue,” says Sandell, who points out that more than 50 percent of people age 65 and over have osteoarthritis. “But it is not just a disease of old age; people get it when they’re young, too.”
Under a multi-year grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), she and her colleagues are studying stem cells in specially bred mice to determine whether there is a correlation between injury and healing.
“Every person has stem cells, and some people are better at repairing than others,” Sandell observes. “We need to find the gene, or genes, for cartilage repair and osteoarthritis in these mice, and target these genes in the development of medications that could be used in humans.
“Every person has stem cells, and some people are better at repairing than others.”
“But like heart disease or obesity, osteoarthritis is a complex disease; the research is difficult and expensive, and improvements are hard to measure. We need to change its image as an inevitable result of old age. It has a molecular start, and it takes a long time to develop. People often don’t realize that their joints are degenerating until late in the process when they begin to hurt.”
Sandell says people can’t change their age but they can reduce the risks of osteoarthritis, which, in addition to genetics, include prior joint injuries and being overweight, through exercise and a healthy diet. “First,” she urges, “no more couch potato. Check with your doctor, then start walking a couple of miles a day. Use—but don’t overuse—your joints.
“Pay attention to what your body is telling you. If your cartilage is okay but your knee is inflamed, ice it,” she advises. “Keeping fit is one of the keys to delaying arthritis.”
Osteoarthritis is not simply “wear and tear” in joints as people get older.
Researchers are studying:
- Tools to detect osteoarthritis earlier
- Tissue engineering—special ways to grow cartilage to replace damaged cartilage
- Medicines to prevent, slow, or reverse joint damage
- Complementary and alternative therapies
- Vitamins and other supplements
- Education to help people better manage their osteoarthritis
- Exercise and weight loss to improve mobility and decrease pain
- Researchers are learning about sex differences that explain why women are more susceptible than men to anterior cruciate ligament (ACL) injuries, which can lead to osteoarthritis. These include structural differences of the knee joint and thigh muscles and differences in the ways male and female athletes move. They are also developing ways to protect young female athletes from these injuries.
- Discovery of the various genetic mutations leading to osteoarthritis could lead to new treatments.
- Longer-lasting materials and designs that more closely mimic natural knee movement are making total joint replacements more suitable for younger, more active osteoarthritis patients.
- Despite the benefits, African American and Asian American patients are less likely than their white counterparts to choose total knee replacement. Also, researchers have found that race is more important than socioeconomic status in these decisions. That is an important first step toward improving access to knee surgery, and to help all patients make informed decisions about their treatment.
- Surgical advances have made hip replacements safer for older patients. This helps older patients who have other conditions that previously would not have allowed them to have the procedure.
- Less invasive surgical approaches and preoperative exercise programs have led to decreased hospital stays and faster recovery. If adopted nationwide, they could lead to major cost savings.
Articles in NIH MedlinePlus magazine are written by professional journalists. All scientific and medical information is reviewed for accuracy by representatives of the National Institutes of Health. However, personal decisions regarding health, finance, exercise, and other matters should be made only after consultation with the reader’s physician or professional advisor. Opinions expressed herein are not necessarily those of the National Library of Medicine. Photos and other images without credit lines are provided by NIH.