Answer :USMLE step 2 Mcq 329:A 34 year old woman with joint pains is suspected of having rheumatoid arthritis





Correct Answer: B

Radiologic erosions represent loss of cortical bone and takes place initially at the margin of the joint where the synovium approximates bone without intervening cartilage; this has been referred to as the 'bare area'. At other portions of the joint, the cartilage protects the subchondral bone from erosion but is itself degraded and damage is manifest as diffuse. In rheumatoid arthritis the intra-articular sites of bone not covered with cartilage are susceptible to direct attack by the rheumatoid synovial pannus. Radiologic evaluation of patients with rheumatoid arthritis may be performed initially to aid in diagnosis but thereafter is used to assess the course of disease, response to therapy, and need for surgical interventions. Radiologic changes that are irreversible include erosion of bone, joint space narrowing, ankylosis, and malalignment. Radiologic evidence of damage (erosion) occurs in almost all patients with rheumatoid arthritis who are seropositive for RF and are followed for more than 5 years. The initial changes may occur early in the course of disease, especially in the hands, where studies show erosion in 20 to 50% of patients in the first 2 or 3 years. Joint subluxation and dislocation are common, especially in the small joints of the hands and feet. Bony ankylosis occurs when cartilage loss is extreme and joint surfaces are juxtaposed allowing fusion of the joint. It is seen in the small joints of the hands, wrists, feet, and ankles; ankylosis of large joints is uncommon in rheumatoid arthritis.


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