Strategies used during a challenging weighted walking task in healthy adults and individuals with knee osteoarthritis

(A) Hip flexion angle at initial contact. The y-axis represents the positive hip flexion angle in degrees (°). The weighted, healthy group and the unweighted, knee OA group had a significantly larger hip flexion angle at initial contact compared to the unweighted, healthy group. (B) Step length with the more affected limb forward. The y-axis is the length of the step in centimeters (cm). The weighted, knee OA group had a significantly shorter step length compared to the weighted, healthy group. (C) Initial double limb support percent with the more affected limb forward. The y-axis is the percent (%) of the gait cycle (out of 100%) that the subject is in double limb support with their more affected limb forward. The weighted, healthy group and the unweighted, knee OA group had a significantly longer double support percent compared to the unweighted, healthy group. Also, the weighted, healthy group and the unweighted, knee OA group had significantly shorter double support percent compared to the weighted, knee OA group. (D) Load rate, or the slope of the vertical GRF curve between heel strike and the first peak in vertical GRF. The y-axis is the change in force normalized to the subject's weight divided by the change in time (N/kg/s). The weighted, healthy group and the unweighted, knee OA group had a significantly lower load rate compared to the unweighted, healthy group. Data are shown with mean±1 standard deviation. Brackets indicate statistically significant differences where p<0.05. Results are presented for four groups: (1) black=unweighted, healthy group; (2) white=weighted, healthy group; (3) gray=unweighted, knee OA group; and (4) stripes=weighted, knee OA group.