What Is Osteoarthritis?
Osteoarthritis (OA) is not a single disease but rather the end result of a variety of disorders leading to the structural or functional failure of one or more of your joints. Osteoarthritis is the most common cause of chronic joint pain, affecting over 25 million Americans. Osteoarthritis involves the entire joint, including the nearby muscles, underlying bone, ligaments, joint lining (synovium), and the joint cover (capsule).
- Osteoarthritis also involves progressive loss of cartilage. The cartilage tries to repair itself, the bone remodels, the underlying (subchondral) bone hardens, and bone cysts form. This process has several phases.
- The stationary phase of disease progression in osteoarthritis involves the formation of osteophytes and joint space narrowing.
- Osteoarthritis progresses further with obliteration of the joint space.
- The appearance of subchondral cysts (cysts in the bone underneath the cartilage) indicates the erosive phase of disease progression in osteoarthritis.
- The last phase in the disease progression involves bone repair and remodeling.
- Joint cartilage is a layer of tissue present at the joint surfaces that sustains joint loading and allows motion. It is gel-like, porous, and elastic. Normal cartilage provides a durable, low-friction, load-bearing surface for joints.
- Articular surface is the area of the joint where the ends of the bones meet, or articulate, and function like a ball bearing.
- Bone remodeling is a process in which damaged bone attempts to repair itself. The damage may occur from either an acute injury or as the result of chronic irritation such as that found in osteoarthritis.
- Collagen is the main supportive protein found in bone tendon, cartilage, skin, and connective tissue.
- Osteophytes are bony outgrowths or lumps, especially at the joint margins. They are thought to develop in order to offload the pressure on the joint by increasing the surface area on which your weight is distributed.
- Synovium is a membrane surrounding the joints that secretes a fluid that lubricates and provides nutrition to tissues.
- Subchondral bone is the part of bone under the cartilage.
- Osteoarthritis is also known as degenerative joint disease.
- Related to its effect on joints, osteoarthritis is sometimes referred to as osteoarthrosis.
What Causes Osteoarthritis?
The causes of osteoarthritis include the following:
- Endocrine: People with diabetes may be prone to osteoarthritis. Other endocrine problems also may promote osteoarthritis development, including acromegaly, hypothyroidism, hyperparathyroidism, and obesity.
- Posttraumatic: Traumatic causes can be further divided into macrotrauma or microtrauma. An example of macrotrauma is an injury to the joint such as a bone break, causing the bones to line up improperly (malalignment), lose stability, or damage cartilage. Microtrauma may occur over time (chronically). An example of this would be repetitive movements or the overuse noted in several occupations.
- Inflammatory joint diseases: This category would include infected joints, chronic gout, and rheumatoid disease.
- Metabolic: Diseases causing errors of metabolism may cause osteoarthritis. Examples include Paget's disease and Wilson disease.
- Congenital or developmental: Abnormal anatomy such as unequal leg length may be a cause of osteoarthritis.
- Genetic: A genetic defect may promote breakdown of the protective architecture of cartilage. Examples include collagen disturbances such as Ehlers-Danlos syndrome.
- Neuropathic: Diseases such as diabetes can cause nerve problems. The loss of sensation may affect how the body knows the position and condition of the joints or limbs. In other words, the body can't tell when it is injured.
- Other: Nutritional problems may cause osteoarthritis. Other diseases such as hemophilia and sickle cell are further examples.
What joints are most often affected by osteoarthritis?
What Are Osteoarthritis Symptoms and Signs?
The following signs and symptoms may be seen:
- Pain: Aching pain, stiffness, or difficulty moving the joint may develop in one or more joints. The pain may get worse with overuse and may occur at night. With progression of this arthritis, the pain can occur at rest.
- Specific joints are affected.
- Fingers and hands: Bone enlargements in the fingertips (first joint) are common. These are called Heberden nodes. They are usually not painful. Sometimes they can develop suddenly and are painful, swollen, and red. This is known as nodal osteoarthritis and occurs in women older than 45 years of age. Another typical joint affected is at the base of the thumb (basal thumb joint or first carpometacarpal joint). This can lead to difficulty gripping and turning keys and opening jars.
- Hip: The hips are major weight-bearing joints. Involvement of the hips may be seen more in men. Farmers, construction workers, and firefighters have been found to have an increased incidence of hip osteoarthritis. Researchers think that a heavy physical workload contributes to OA of the hip and knee.
- Knees: The knees are also major weight-bearing joints. Repetitive squatting and kneeling may aggravate osteoarthritis.
- Spine: Osteoarthritis of the spine can cause bone spurs or osteophytes, which can pinch or crowd nerves and cause pain and potentially weakness in the arms or legs. Osteoarthritis affecting the low back can lead to chronic low back pain (lumbago). Osteoarthritis in the spine leads to degenerative disc disease (spondylosis).
When Should I Call the Doctor About Osteoarthritis?
When to call the doctor
- Pain with no benefit from common pain relievers
- Confusion regarding the diagnosis (Osteoarthritis can be confused with rheumatoid arthritis and gouty arthritis.)
- Disability or loss of mobility, especially if sudden
When to go to the hospital
- Trauma: Injuries from trauma such as falls, especially sports-related injuries, may require X-rays.
- Signs of infection: Fever, redness, or joint swelling may indicate joint inflammation or joint infection. A joint infection is a serious problem requiring prompt diagnosis and antibiotic therapy. Gout can also have similar symptoms.
- Sudden inability to walk, bear weight, or a significant change in function would be a reason to seek immediate medical help.
How Do Health Care Professionals Diagnose Osteoarthritis?
- X-rays: Approximately one-third of people with osteoarthritis on X-rays have symptoms such as pain or swelling. X-rays can show narrowing of the space between the joint (articular surface), osteophytes, cyst formation, and hardening of the underlying bone. Scoring systems have been used by doctors to assess the extent of the bony changes on X-rays. Separate scoring systems for the different joints have been studied and found to be predictive of disease status. An important finding from these studies was that the presence of osteoarthritis of the hands was a predictive sign of deterioration of the knee joint. In other words, people with finger joint osteoarthritis were more at risk to show a rapid progression of their knee osteoarthritis.
- MRI: This study is a complex, noninvasive imaging technique that is unlike X-rays. X-rays provide information mainly on bones. However, MRI is capable of visualizing all structures within the joint. MRI technology is sophisticated and requires an expert to interpret the study.
- CT scan: This study may be used to image a joint. CT scanning mainly provides information on the bony structures of the joint but in greater detail than plain X-rays.
- Joint fluid analysis: Fluid may be extracted from the knee with a needle and syringe when the diagnosis is uncertain or if an infection is suspected.
- Blood tests: No currently accepted blood test or marker for this disease exists. Blood tests may be drawn in cases in which infection is suspected.
What Are the Home Remedies for Osteoarthritis?
Lifestyle changes may delay or limit osteoarthritis symptoms. These are common home remedies:
- Weight loss: One study suggested that, for women, weight loss may reduce the risk for osteoarthritis in the knee.
- Exercise: Regular exercise may help to strengthen the muscles and potentially stimulate cartilage growth. Avoid high-impact sports. The following types of exercise are recommended: range of motion, strengthening, and aerobic.
- Diet: While there is no specific osteoarthritis diet, supplements of antioxidant vitamins C and E may provide some protection. Vitamin D and calcium are recommended for strong bones. The recommended daily dose of calcium is 1,000 mg-1,200 mg. The current guideline for vitamin D is 400 IU per day.
- Heat: Hot soaks and warm wax (paraffin) application may relieve pain.
- Orthoses: These assistive devices, such as neck braces and knee braces, are used to improve function of moveable parts of the body or to support, align, prevent, or correct deformities. Splints or braces help with joint alignment and weight redistribution. Other examples include walkers, crutches or canes, and orthopedic footwear.
- Over-the-counter (OTC) medications
- Acetaminophen (Tylenol) is the first drug recommended for osteoarthritis.
- Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for arthritis pain. These include aspirin, ibuprofen (Motrin or Advil), naproxen (Aleve), and ketoprofen (Orudis).
- Newer OTC preparations include chondroitin and glucosamine sulfate, which are natural substances found in the joint fluid. Chondroitin is thought to promote an increase in the making of the building blocks of cartilage (collagen and proteoglycans) as well as having an anti-inflammatory effect. Glucosamine may also stimulate production of the building blocks of cartilage as well as being an anti-inflammation agent. Glucosamine was found to increase blood sugar in animal studies, so people with diabetes should consult their doctor first.
- Arthritis self-help course: The Arthritis Foundation offers an educational program on the causes and treatment of arthritis. Exercise, nutrition, relaxation, and pain-management programs are covered as well as ways to communicate with your doctor. Completion of the program reduced pain by 20% and doctor visits by 40%.
What Is the Treatment for Osteoarthritis?
The overall goal of treatment is early elimination of risk factors, early diagnosis and surveillance of the disease, and appropriate treatment of pain. It's also important to help people regain their mobility. These goals may be reached through a logical approach to care, including the overlapping of treatment that does not involve medications and treatment with medication and possibly surgical management.
Treatment that does not involve medications includes education, physical and occupational therapy, weight reduction, exercise, and assistive devices (orthoses).
What Are the Medications for Osteoarthritis?
Initially, simple over-the-counter pain relievers such as acetaminophen are recommended, followed by NSAIDs. Prescription NSAIDs may be needed if the over-the-counter medications are ineffective. A new generation of prescription NSAIDs are the COX-2 medicines (celecoxib [Celebrex]). The COX-2 drugs have fewer reported gastrointestinal side effects but similar results compared to the typical NSAIDs.
The antidepressant duloxetine (Cymbalta) is now approved by the Food and Drug Administration (FDA) for chronic musculoskeletal pain (joint and muscle pain). This medication works on neurotransmitters in the brain that control pain perception and has been shown to decrease chronic low back pain and pain caused by knee osteoarthritis.
Slideshow: Exercises for Knee Osteoarthritis and Joint Pain
What Is the Surgery for Osteoarthritis?
Surgery may relieve pain and improve function.
- Arthroscopy is the examination of the inside of a joint using a small camera (endoscope). Arthroplasty is the repair of a joint in which the joint surfaces are replaced with artificial materials, usually metal or plastic.
- Osteotomy is incision or cutting of bone.
- Chondroplasty is surgical repair of the cartilage.
- Arthrodesis is a surgical fusion of the bony ends of a joint preventing joint movement. For example, fusion of an ankle joint prevents any further joint movement of the ankle itself. This is done as a result of many years of significant joint pain resulting from a previous significant injury or severe osteoarthritis. The procedure is performed to help block further pain by preventing any further joint movement.
- Joint replacement is removal of diseased or damaged bony ends and replacement with a manmade joint composed of a combination of metal and plastic. Knee joint replacement and hip replacement are the most common. Some joints, such as those of the spine, cannot be replaced presently.
What Is the Follow-up for Osteoarthritis?
Use medications in the prescribed manner and watch for side effects. This is especially important with the NSAIDs. Acetaminophen, however, may also have side effects if you take too much or if you have liver disease.
How Can You Prevent Osteoarthritis?
No absolute way to prevent osteoarthritis is available. Lifestyle changes may reduce or limit symptoms.
What Is the Prognosis for Osteoarthritis?
A single prognosis is difficult to establish because of the variety of factors influencing the disease. It also may be important to look at the particular joint involved rather than lumping all the joints together to predict the outcome. For example, the prognosis for hip osteoarthritis may be different than the prognosis for hand osteoarthritis. Symptoms may not be able to be predicted based on X-rays, because some people experience a great deal of pain with only mild osteoarthritis on X-ray, and some people experience only mild pain while their X-rays show severe osteoarthritis. But a few studies may predict joint deterioration.
Some findings suggest that the following are true:
- Narrowing of the joint space seems to be linked with deterioration of the condition.
- The presence of osteoarthritis of the hands is a predictive sign for deterioration of the knee joints.
- People with rapid progression seemed to have knee pain upon entry into clinical studies.
Future research into causes of joint pain in patients with osteoarthritis will likely lead to improved treatments. Ongoing scientific studies are encouraging and include work looking at the effects of antibodies against nerve growth factor, which seems to play a role in pain perception in those afflicted by osteoarthritis of the knees and hips.
A normal or unaffected joint demonstrating the articular surfaces and the joint space. The stationary phase of disease progression in osteoarthritis involves the formation of osteophytes or joint space narrowing. Osteoarthritis progresses further with obliteration of the joint space. The appearance of subchondral cysts (cysts in the bone underneath the cartilage) indicates the erosive phase of disease progression in osteoarthritis. The last phase in the disease progression involves bone repair and remodeling. Large osteophytes form.
Reviewed on 10/11/2018
Klippel, John H., et al., eds. Primer on the Rheumatic Diseases. 13th ed. New York: Springer and Arthritis Foundation, 2008
Rennie, N.G., et al. "Presence of Gout Is Associated with Increased Osteoarthritis Prevalence and Severity." Arthritis and Rheumatism 63.10 Oct. 2011.