Measurement of stiffness in the metacarpophalangeal joint: the arthrograph.

A new type of finger arthrograph is described that evaluates the stiffness parameters of the metacarpophalangeal joint of the index finger at 10 degrees increments of flexion and extension. Stiffness is evaluated in terms of the energy loss per cycle (of amplitude 4 degrees), at every 10 degrees interval from 4 degrees to 94 degrees of flexion and by the mid-position torque and the mean slope of the least-squares fitted line through the graph of resistive torque against angular displacement. The instrument is simple to use, quick and comfortable for the patient, and gives reproducible results.