Normal vibration perception thresholds in rheumatoid arthritis--evidence against the neurogenic theory of articular stiffness.

Patients with arthritis consistently report joint stiffness, but recent attempts to quantify joint stiffness objectively have been unable to demonstrate any increase in stiffness in arthritic joints. This discrepancy between subjective and objective measures may be explained by postulating decreased mechano-receptor thresholds in arthritis (the neurogenic hypothesis). To test this hypothesis digital cutaneous mechano-receptor threshold (vibration perception threshold, VPT) was measured in 50 patients with rheumatoid arthritis, comparing results with previously established normative data. No difference was found between RA and normals in respect to VPT. This result does not support the theory that altered mechano-receptor thresholds are important in the experience of joint stiffness in rheumatoid arthritis, but further data on articular mechano-receptor thresholds are required before the hypothesis can be rejected.