Copyright 2009
Definition
Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease of the synovial membranes of multiple joints. The disease can affect large joints such as the hips, knees, shoulders, and elbows as well as smaller joints. The American Rheumatism Association states that 4 of the following criterium are met to make the diagnosis of rheumatoid arthritis.
- Morning stiffness lasting longer than 1 hour before improvement
- Arthritis involving 3 or more joints
- Arthritis of the hand, particularly involvement of the proximal interphalangeal (PIP) joints, metacarpophalangeal (MCP) joints, or wrist joints
- Bilateral involvement of joint areas (ie, both wrists, symmetric PIP and MCP joints)
- Positive serum rheumatoid factor (RF)
- Rheumatoid nodules
- Radiographic evidence of RA
It is characterized by an increased autoimmune response with increased inflammatory factors such as tumor necorsis factor and interleukin-1. Synovial tissue is one of several structures that can be affected. It is seen in about 1% of the population of the US. Patients can have painful arthritic knees which eventually may need surgical management if medical management fails.
It is caused by an autoimmune response of the body against its own tissue. This inflammatory process can cause damage to articular cartilage of the knee and inflammation of the synovium which can be painful and debilitating.
Diagnosis is suspected clinically by a history of rheumatoid arthritis with pain in the knee. The knee is rarely the first joint to be affected, so it is relatively easy to make the diagnosis of rheumatoid arthritis of the knee from a simple history and physical. X-rays should always be obtained to determine the amount of joint destruction and MRI is usually unecessary.
Imaging includes the use ofplain x-rays which usually are different in nature from the degenerative process involved with osteoarthritis (degenerative joint disease). Rheumatoid arthritis has joint space narrowing on standing radiographs with few osteophytes which are in abundance with degenerative joint disease.
Treatment options depend on the severity of the disease and health of the patient. If medical management has failed, total knee replacement is the next obvious step.
References
http://emedicine.medscape.com/article/808419-overview