Foot and Ankle Joint Biomechanical Adaptations to an Unpredictable Coronally Uneven Surface

Abstract

Coronally uneven terrain, a common yet challenging feature encountered in daily ambulation, exposes individuals to an increased risk of falling. The foot-ankle complex may adapt to improve balance on uneven terrains, a recovery strategy which may be more challenging in patients with foot-ankle pathologies. A multisegment foot model (MSFM) was used to study the biomechanical adaptations of the foot and ankle joints during a step on a visually obscured, coronally uneven surface. Kinematic, kinetic and in-shoe pressure data were collected as ten participants walked on an instrumented walkway with a surface randomly positioned ±15 deg or 0 deg in the coronal plane. Coronally uneven surfaces altered hindfoot–tibia loading, with more conformation to the surface in early than late stance. Distinct loading changes occurred for the forefoot–hindfoot joint in early and late stance, despite smaller surface conformations. Hindfoot–tibia power at opposite heel contact (@OHC) was generated and increased on both uneven surfaces, whereas forefoot–hindfoot power was absorbed and remained consistent across surfaces. Push-off work increased for the hindfoot–tibia joint on the everted surface and for the forefoot–hindfoot joint on the inverted surface. Net work across joints was generated for both uneven surfaces, while absorbed on flat terrain. The partial decoupling and joint-specific biomechanical adaptations on uneven surfaces suggest that multi-articulating interventions such as prosthetic devices and arthroplasty may improve ambulation for mobility-impaired individuals on coronally uneven terrain.