Residual dynamic arch index but balanced plantar loading after medializing calcaneal osteotomy in children with symptomatic flexible flatfoot: a matched-pair pedobarographic study.

Abstract

Flexible flatfoot alters plantar loading and may necessitate surgery. Medializing calcaneal osteotomy (MCO) aims to restore the foot tripod. We compared dynamic pedobarographic parameters in children with flexible flatfoot after MCO with those of matched controls, with the arch index as the primary outcome. This matched-pair comparative study included children who underwent MCO ≥12 months previously and healthy controls matched 1 : 1 by sex, age, and BMI. Dynamic plantar pressure was recorded. Outcomes included arch index, regional plantar impulse, relative loading index across hindfoot/midfoot/forefoot, foot axis angle, and plantar phase-times normalized to stance. Mixed-effects multivariable linear regression was utilized, adjusted for age, sex, and BMI. Twenty-one children with flexible flatfoot were matched to 21 controls (38 feet per group). The mean follow-up after MCO was 3.45 years; 17/21 patients underwent concomitant gastrosoleus recession. Adjusted arch index remained higher in the flexible flatfoot group [mean difference = 0.06; 95% confidence interval (CI) = 0.03-0.08; P < 0.001], and equivalence within ±0.05 was not demonstrated (90% CI = 0.031-0.079). Midfoot impulses and regional foot loading were comparable between groups, whereas the flexible flatfoot group showed a more externally rotated foot axis angle. Total stance time did not differ, but the forefoot push-off phase (FFPOP) was 7.49% shorter in the flexible flatfoot group. A higher BMI was independently associated with a higher arch index and midfoot impulse. After MCO, children demonstrated residual differences in arch index and foot axis angle despite balanced plantar load-sharing and preserved stance timing. A shorter FFPOP suggests subtle late-stance propulsive adaptation, potentially influenced by calf lengthening.