Effect of orthotics and footwear on static rearfoot kinematics

This study examined the effect of foot orthotics and footwear on static rearfoot kinematics. Thirty-four subjects (5 males, 29 females) from physical therapy clinics and the college community gave informed consent to participate. Subject age was 42 (18) years; subject height was 1.7 (0.1) meters; subject body mass was 72.6 (12.1) kg. Markers were placed on specific sites of the lower leg and calcaneus to determine the rearfoot angle. Rearfoot angle was measured with a goniometer and digitized with video-based software (Ariel Performance Analysis System). A calcaneal mold was utilized to determine the position of the calcaneus in the shod conditions. Static rearfoot angles were measured in the following conditions: barefoot (B), barefoot with the calcaneal mold (BM), barefoot with the calcaneal mold plus the orthotic (BMO), shod with the calcaneal mold (SM), and shod with the calcaneal mold plus the orthotic (SMO). An independent t-test analyzed differences between each condition as measured with the APAS and goniometer. A one-way analysis of variance (ANOVA) was utilized to determine statistically significant differences among the 5 foot conditions (p ≤ 0.05). Independent t-tests revealed no significant differences (p > 0.05) between the APAS and goniometer measurements within each condition. One-way ANOVA showed a significant difference (p ≤ 0.01) among the five conditions as measured by APAS. Post-hoc analysis determined that the difference between BM and SM; and the BM and SMO conditions were significantly different (p ≤ 0.01). It was observed that the orthotic slightly decreased the amount of calcaneal eversion in the standing position. The shoes worn in the study, though neutral in construction, did significantly alter rearfoot kinematics in comparison to BM. Key PointsPrevious literature concerning the effect of orthotics on lower extremity alignment is inconclusive.This study concurs with the work of others as to the effectiveness of orthotics on the reduction of calcaneal eversion.Even though the kinematic differences were small, subjects still reported a positive effect on their level of comfort with the orthotics as compared to not wearing the orthotic.