The dynamic vertical force distribution during level walking under normal and rheumatic feet.

Normal subjects and patients with rheumatoid arthritis and varying degrees of foot involvement have been studied using an apparatus which measures the dynamic force distribution under the foot during walking. There was a significant change in the walking pattern of the patients, expressed in slowing the speed of walking, lowering the heel-strike and push-off impacts, increasing the double-support period and reducing the amount of impulse taken by the forefoot. As a result, the localized peak loads and impulses were not higher than those of the control group, but moved from the medial side of the foot towards the centre, and the ratio of peak to average load (force concentration factor) at this region increased.