Clinical determinants of plantar forces and pressures during walking in older people.

The aim of this study was to determine the extent to which clinical tests of structural characteristics of the foot and ankle could account for variation in the magnitude of regional forces and pressures under the foot during walking in older people. Plantar forces and pressures were obtained from 172 older people (53 men, 119 women) aged 62-96 years (mean 80.0, S.D. 6.4) using a floor-mounted resistive sensor mat system. Subjects also completed tests of foot posture, range of motion, strength, sensation and toe deformity. Multiple regression analysis was then used to determine which clinical variables were most strongly correlated with plantar forces and pressures. Maximum forces and peak pressures under most regions of the foot were largely explained by differences in bodyweight, with some important exceptions. Loading under the midfoot was associated with the arch index, loading under the first metatarsophalangeal joint (1st MPJ) was associated with 1st MPJ range of motion, and loading under the hallux was associated with hallux plantarflexor strength, 1st MPJ range of motion and the degree of hallux valgus deformity. Clinical measurements accounted for 13-53% of the variance in maximum force and 4-40% of the variance in peak pressures. These findings indicate that structural foot and ankle characteristics identified from clinical measurements can explain some key aspects of plantar loading patterns of the foot. This information provides further insights into the dynamic function of the foot, which might assist in the development of interventions for pressure-related foot complaints in older people.