Quantification of morning stiffness in patients affected by rheumatoid arthritis

In addition to joint swelling and tenderness, patients with rheumatoid arthritis (RA) commonly experience morning symptoms of joint stiffness associated with pain that result in impaired function causing morbidity and productivity loss with early disease as well as those with low disease activity or remission.

Although RA patients recognize morning stiffness as being one of the four most significant symptoms to manage, validated morning stiffness patient-reported outcome (PRO) measures are lacking. Therefore, we have developed an approach to objectively quantify finger joint stiffness. The device has been approved by the ethical committee for the use in patients, and has also already obtained a national technical certification.

The tool enables quantitative measurements of the passive resistance of an affected MCP joint against an externally applied torque while the finger was fixed in the device and passively moved from a completely extended position (referred to as 0°) to a flexed position of 60°. Measurement related sensors and advanced analysis algorithms for the investigation of resulting hysteresis curves enabled both the stiffness and dissipated energy to be evaluated at definite flexion-extension angles.