PEEK in Pediatric Calcaneal Lengthening: Alternative or Compromise? A Randomized Controlled Trial

The optimal interposition material for lateral calcaneal lengthening osteotomy (LCLO) in pediatric flexible flatfoot remains uncertain. Iliac autogenous bone graft (AIBG) provides structural support but requires donor-site harvest; polyetheretherketone (PEEK) cages avoid a second incision.

This randomized controlled trial included 60 unilateral feet in 60 patients allocated 1:1 to PEEK or AIBG. Weight-bearing radiographs were obtained preoperatively, immediately postoperatively, at 3 months, 6 months, 12 months, and final follow-up (minimum 24 months; mean 29 months). Six angles were assessed by two blinded observers. Longitudinal outcomes were analyzed using two-way repeated-measures ANOVA with Greenhouse-Geisser correction when required and Bonferroni-adjusted post-hoc comparisons.

Final American Orthopaedic Foot & Ankle Society (AOFAS) scores were 87.04±7.42 with PEEK and 88.31±6.56 with AIBG (p=0.489). All six angles showed their largest correction immediately postoperatively, followed by smaller changes in the same corrective direction. Time effects were significant, whereas treatment × time interactions were nonsignificant. Preoperative-to-immediate correction was significant for all angles; later changes were smaller. Union occurred in all feet. Composite complications were higher with PEEK (27% vs 3%; p=0.026).

PEEK and AIBG produced similar functional and radiological trajectories, but the higher complication rate (27% vs 3%) with PEEK supports further comparative evaluation. The results illustrate how structural correction can be distinguished from later remodeling when repeated radiographic measures are analyzed.