Treatment of spastic varus/ equinovarus foot with split-tendon transfers in cerebral palsy: How does it affect the hindfoot motion?

Abstract

Introduction: The flexible spastic varus foot in cerebral palsy is commonly corrected by split-tendon transfer of tibialis anterior or tibialis posterior. These tendon transfers are said to preserve hindfoot motion, which is until now not been proven. Therefore, the aim of the study was to show the hindfoot motion following split-tendon transfer in comparison to a midtarsal arthrodesis.

Materials and methods: A retrospective study was done on patients with flexible spastic varus foot in cerebral palsy who underwent a combined split-tendon transfer of tibialis anterior and posterior. Patients with a rigid foot deformity underwent a midfoot arthrodesis. These children and normal children served as controls. An instrumented gait analysis was done in all patients before and at follow-up. A statistical analysis was done using 2-factor ANOVA with repeated measures on time.

Results: Thirteen children underwent a combined split-tendon transfers of tibialis anterior and posterior muscles and 14 children midtarsal arthrodesis. The mean follow-up was 2.4 (SD=0.8) years for flexible varus foot and 1.9 (SD=0.7) years for rigid foot deformity. The preoperative hindfoot range of motion in eversion-inversion was 54% and 49% of TD controls in flexible varus foot and rigid foot deformity respectively. At follow-up, it reduced further to 45% and 42% of TD controls in the respective groups.

Conclusion: Both flexible and rigid hindfoot deformity reduced the hindfoot motion. However following surgery, the hindfoot motion reduced further and was identical in both groups independent of the type of surgery. This indicates a tenodesis-effect of split-tendon transfers on the hindfoot.

Keywords: Cerebral palsy; Chopart arthrodesis; Hindfoot kinematics; Midtarsal arthrodesis; SPLATT; SPOTT; Spastic varus/equinovarus foot; Split-tendon transfers; Tibialis anterior; Tibialis posterior.