Osteoarthritis

Osteoarthritis is the most common form of arthritis. It causes deterioration of the joint cartilage and formation of reactive new bone at the margins and subchondral areas of the joints. This chronic degeneration results from a breakdown of chondrocytes, most often in the hips and knees.

Osteoarthritis occurs equally in both sexes, after age 40, with the earliest symptoms occurring in middle age and progressing with advancing age.

Depending on the site and severity of joint involvement, disability can range from minor limitation of the fingers to near immobility in people with hip or knee disease. Progression rates vary; joints may remain stable for years in the early stage of deterioration.

Causes and pathophysiology

Primary osteoarthritis may be related to aging, but researchers don't understand why. This form of the disease seems to lack any predisposing factors. In some patients, it may be hereditary.

Secondary osteoarthritis usually follows an identifiable event - most commonly a traumatic injury or a congenital abnormality such as hip dysplasia. Endocrine disorders such as diabetes mellitus, metabolic disorders such as chondrocalcinosis, and other types of arthritis also can lead to secondary osteoarthritis.

Signs and Symptoms

Osteoarthritis often develops slowly, and some people may not experience any signs or symptoms. However, osteoarthritis can cause the following signs and symptoms:

• Pain in a joint during or after use, or after a period of inactivity
• Discomfort in a joint before or during a change in the weather
• Swelling and stiffness in a joint, particularly after using it
• Bony lumps on the middle or end joints of your fingers or the base of your thumb
• Loss of joint flexibility

Diagnostic tests

X-rays of the affected joint may help confirm the diagnosis, but findings may be normal in the early stages. X-ray studies may require many views. Typical findings include a narrowing of the joint space or margin, cystlike bony deposits in the joint space and margins, sclerosis of the subchondral space, joint deformity caused by degeneration or articular damage, bony growths at weight-bearing areas, and joint fusion in patients with erosive, inflammatory osteoarthritis.

Synovial fluid analysis can be used to rule out inflammatory arthritis.

Radionuclide bone scan can also be used to rule out inflammatory arthritis by showing normal uptake of the radionuclide.

Arthroscopy is used to identify soft-tissue swelling by showing internal joint structures.

Magnetic resonance imaging produces clear crosssectional images of the affected joint and adjacent, bones. Results also show disease progression.

Neuromuscular tests may disclose reduced muscle strength (reduced grip strength, for example).

Treatment

To relieve pain, improve mobility, and minimize disability, treatment includes medications, rest, physical therapy, assistive mobility devices and, possibly, surgery.

Medications include aspirin and other salicylates and such nonsteroidal anti-inflammatory drugs as phenylbutazone, propoxyphene, indomethacin, fenoprofen, and ibuprofen. In some patients, intra-articular injections of corticosteroids may be necessary. Such injections, given every 4 to 6 months, may delay nodal development in the hands.

Adequate rest is essential and should be balanced with activity. Physical therapy includes massage, moist heat, paraffin dips for the hands, supervised exercise to decrease muscle spasms and atrophy, and protective techniques for preventing undue joint stress. Some patients may reduce stress and increase stability by using crutches, braces, a cane, a walker, a cervical collar, or traction. Weight reduction may help an obese patient.

In some cases, a patient with severe disability or uncontrollable pain may undergo surgery, including:

• arthroplasty (partial or total) - replacement of the deteriorated part of a joint with prosthetic appliance.
• arthrodesis - surgical fusion of bones, used primarily in the spine (laminectomy)
• osteoplasty- scraping and lavage of deteriorated bone from the joint
• osteotomy - excision or cutting of a wedge of bone(usually in the lower leg) to change alignment and relieve stress.

Prevention

You can take steps to help prevent the development of osteoarthritis or to help prevent the progression of this condition. These steps include:

• Weight control.
• Protect your joints from serious injury or repeated minor injuries to decrease your risk of damaging cartilage. Repeated minor injuries include those from job-related activities such as frequent or constant kneeling, squatting, or other postures that place stress on the knee joint.
• Exercise can help reduce joint pain and stiffness.