NORMAL VIBRATION PERCEPTION THRESHOLDS IN RHEUMATOID-ARTHRITIS - EVIDENCE AGAINST THE NEUROGENIC THEORY OF ARTICULAR STIFFNESS

Patients with arthritis consistently report joint stiffness, but recen t attempts to quantify joint stiffness objectively have been unable to demonstrate any increase in stiffness in arthritic joints. This discr epancy between subjective and objective measures may be explained by p ostulating decreased mechano-receptor thresholds in arthritis (the neu rogenic 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 prev iously 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 experie nce of joint stiffness in rheumatoid arthritis, but further data on ar ticular mechano-receptor thresholds are required before the hypothesis can be rejected.