Reliability of measurements of pressures applied on the foot during walking by a computerized insole sensor system

Objective: To evaluate the reliability of measurements of foot pressures while walking using the F-scan computerized system with various insole sensors. Design: Ten healthy subjects were studied. Each used four different pairs of insoles while walking for three 6-second epochs per insole. Peak pressures were recorded at the hindfoot, midfoot, and forefoot and analyzed. Each insole was made of pressure-sensitive 25mm(2) cells, embedded in protective backing, and scanned electronically every 50 to 100msec. Setting and Participants: Conventional tile floor in a gait laboratory on 10 consecutive normal subjects. Results: The mean +/- standard deviation peak pressure recorded at the hindfoot was 11.1 +/- 2.0psi; at the midfoot, 3.5 +/- 1.5psi; and at the forefoot, 11.3 +/- 2.6psi. The intrasubject mean differences were 0.2psi at the hindfoot, 0.4psi at the midfoot, and 0.3psi at the forefoot. The data suggest that variability between different insoles is not significant. Conclusion: The pressure data show these insoles to be sufficiently reliable for use in patients when knowledge of foot pressure distribution is important for the relief of pain, and for designing and assessing appropriate corrective measures to relieve excessive pressure on the foot and to prevent development of pressure ulcers.