A 50-year-old woman with seronegative rheumatoid arthritis had tenderness in the right middle finger for about 2 weeks. Inspection revealed no swelling. The most sensitive test for flexor tenosynovitis or PIP joint arthritis is to examine the passive range of flexion of all fingers by bending each finger separately while the MCP joints are held extended. Normally, the fingertip easily touches the thenar of the palm. This patient had a painful limitation of flexion in the middle finger, and the distance between the fingertip and thenar was 10 mm, which was recorded in the patient's file.
Examining finger flexion in a patient with rheumatoid arthritis