Foot tissue stress in chronic ankle instability during the stance phase of cutting

Abstract

Lower limb biomechanics of chronic ankle instability (CAI) individuals has been widely investigated, but few have evaluated the internal foot mechanics in CAI. This study evaluated bone and soft tissue stress in CAI contrasted with copers and non-injured participants during a cutting task. Integrating scanned 3D foot shapes and free-form deformation, sixty-six personalized finite element foot models were developed. Computed Achilles tendon forces and measured regional plantar pressure were applied as boundary loading conditions for simulation. It was observed that the primary group differences in foot stress occurred during midstance and heel-off phases of the cutting task. Specifically, healthy individuals had significantly higher stress in the talus and soft tissue around the talus compared to CAI participants. In contrast, CAI participants had significantly higher stress in the cuneiforms and lateral forefoot bones during mid-stance and push-off phases. CAI participants appeared to adopt a protective strategy by transferring greater force to the lateral forefoot at the heel-off phase while lowering stress around the talus, which may be associated with pain relief near the ankle. These findings suggest further attention should be placed on internal stress in CAI at the push-off phase with implications for long-term foot adaptation.

Keywords: Finite element analysis; Free-form deformation; Host mesh fitting; Lateral ankle sprain; Personalized foot model.

Fig. 1

Illustration of the complete pipeline for personalized FE model development. A Personalized foot model reconstruction based on host-mesh free form deformation. B Applications of the boundary and loading conditions for finite element simulation

Fig. 2

Pre-study mesh convergence analysis. Representative mesh convergence for calcaneus: results from different mesh sizes with same material properties and loading conditions (A) and different mesh sizes of calcaneus (B)

Fig. 3

Acquisition of boundary loading conditions for finite element simulation. A Achilles tendon force calculation and output, and B regional plantar pressure definition and acquisition. A_A and M_A mean the ankle angle and ankle moment in the sagittal plane, respectively. L_M means the moment arm

Fig. 4

Comparisons of peak von Mises stress in five different regions of soft tissue among three groups during the stance phase of the cutting task