Modifying ankle foot orthosis stiffness in patients with calf muscle weakness: gait responses on group and individual level.

The group-level comparison of stiffness levels for walking energy cost was not significant, so the study does not show that one stiffness level is best for all patients. The individual optimal stiffness was identified from repeated testing in the same participants, so it may not be reproducible when a new AFO is fitted without measuring several stiffness levels. Data for walking energy cost were analysed in 36 participants because one participant had a technical error in the K5 condition. AFO generated power was analysed in 29 participants because of marker processing problems and three participants using a walking stick during gait analysis. The tested stiffness range did not cover usual care AFOs, because the lowest tested stiffness was stiffer than common usual care AFOs and the stiffest tested AFO was not rigid. Only three valid steps were analysed for gait biomechanics per person. The participants had different diagnoses, unilateral or bilateral involvement, and muscle strength, so the results may not apply to a more homogeneous patient group.

Funded by Prinses Beatrix Spierfonds. No other funding or conflict of interest statements are reported in the supplied text.

Do not prescribe K2 for every patient because it was the group average optimum. The group-level difference between stiffness levels for walking energy cost was not significant, and the most efficient stiffness varied between individuals.