Excessive medial rotation of the tibia and the problems associated with this motion has been linked to excessive pronation at the foot. One cause of excessive pronation is an inverted forefoot to rearfoot ratio. The purpose of this study was to examine the effect that custom rigid forefoot orthotics has on the amount of tibial rotation experienced by cyclists with an inverted forefoot to rearfoot ratio. Nine (one female, eight males) healthy cyclists between the ages of 24-50 with a forefoot inversion of 6 degrees or more were filmed riding their bicycles with and without custom forefoot orthotics. Light reflective markers placed on the subject's right leg were used in conjunction with the PEAK two dimensional video analysis system to measure the angular motion of the tibial tuberosity from top dead center (TDC) to bottom dead center (BDC) during five randomly chosen revolutions. A paired two tailed t-test was used to analyze the data. As a group, the subjects showed no statistically significant differences between the two conditions (p = 0.147). However, when the least experienced cyclist was omitted from the group due to highly abnormal motion, statistics revealed a significant difference (p = 0.013) between the two conditions. When cycling with orthotics, seven subjects showed a decrease in rotation ranging from 1.5 to 4.0 degrees, one subject demonstrated no change, and one subject demonstrated an increase in rotation of 2.5 degrees. Anecdotal reports from five subjects approximately one month after receiving the orthotics were highly supportive of their utilization. Based on the results of this study, the authors feel that when treating experienced cyclists with a forefoot varus or similar condition, custom forefoot orthotics may help decrease medial rotation of the tibia. This decrease in rotation helps improve knee alignment to a more vertical position and enhance anatomic function.
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