Use of computerized insole sensor system to evaluate the efficacy of a modified ankle-foot orthosis for redistributing heel pressures.

OBJECTIVE Evaluation of orthosis purported to decrease pressure on the heel while walking. DESIGN The Multipodus System is an orthotic device, designed for this purpose, that can be worn with flat or rocker bottom boot. Ten subjects underwent four trials: first, an initial walk wearing their usual shoes, then using the orthosis on the left, with a flat bottom boot, then with a rocker bottom boot, and a final walk. Pressures exerted on the plantar surface of the hindfoot, midfoot, and forefoot were measured electronically and analyzed. SETTING AND PARTICIPANTS Ten consecutive normal subjects were tested on a conventional tile floor in a gait laboratory. RESULTS Peak pressures in the initial walk averaged: heel, 9.6 +/- 2.3psi; midfoot, 2.6 +/- 1.7psi; and forefoot, 10.3 +/- 2.6psi. Pressures on the foot were redistributed significantly when the orthosis was used. Heel pressure was reduced significantly compared to the ordinary shoes using both the flat bottom boot (5.0 +/- 1.2psi, a decrease of 48% [p = .0001]) and the rocker bottom boot (4.5 +/- 1.5psi, a decrease of 53% [p = .0001]). Pressure was increased at the midfoot with both the flat bottom boot (6.6 +/- 3.2psi, an increase of 61% [p = .0001]) and the rocker bottom boot (6.8 +/- 2.9psi, an increase of 62% [p = .0001]). Pressures at the forefoot decreased 19% (8.3psi) with the flat bottom boot and 32% (7.0psi; p = .0003) with the rocker bottom boot. CONCLUSIONS Redistribution of pressure on the foot with orthosis is characterized by reduction at the hindfoot and forefoot and increase at the midfoot with both the flat and rocker bottom boots, thereby promoting healing of calcaneal and forefoot ulcers. The integrity of the midfoot, however, must not be compromised.