Stiffness in the metacarpo-phalangeal joints of young adults.

A simple design of arthrograph is described and used to study the stiffness of the metacarpo-phalangeal joints of 55 subjects between the ages of 18 and 25. The apparatus and experimental technique produced results which were repeatable to within four percent. Results obtained when the tests were conducted at different angles of flexion showed that the direction of approach to the angle of flexion was important. For example, if the same angular position were approached first from a greater angle of flexion and then from a smaller angle of flexion, the resulting measured resistive torques were different. However, the two different values were repeatable and not dependent on the order of testing. Stress relaxation of the soft tissues surrounding the joint was observed while the variation in the equilibrium position (resting angle of flexion) was seen to be from 16 to 44 deg (mean 33.2). Stiffness was strongly correlated with subject mass and weakly correlated with wrist circumference. Women exhibited lower joint stiffness than mean but some of this difference may be due to their lower body mass.