Finite element analysis of the impact of running foot strike pattern on patellar cartilage stress.

Abstract

This study aimed to compare the effects of forefoot strike (FFS) and rearfoot strike (RFS) running on patellar cartilage stress, strain, contact area, and patellar movement using finite element analysis. Twenty-four healthy runners were assigned to RFS (n = 12) or FFS (n = 12) groups based on their habitual foot strike pattern. Biomechanical data were collected during running at 3 m/s. A 3D finite element model of the patellofemoral joint was developed from MRI data. All finite element simulations were performed on a single subject-specific knee model, with loading conditions representing the group-averaged biomechanics of RFS and FFS patterns. Knee angle and quadriceps muscle forces derived from OpenSim were applied as boundary conditions to simulate cartilage mechanical behavior. No significant differences were observed between the FFS and RFS in peak knee angles or in the peak forces of the quadriceps muscle forces. The FFS exhibited lower peak values in patellar cartilage stress, strain, and contact area compared with the RFS. In both foot strike patterns, stress concentration initially shifted from the central ridge to the lateral cartilage and then back to the central ridge, with peak stress localized in the lateral cartilage. Patellar movement was similar between groups, characterized by lateral, posterior, and inferior translation, as well as flexion, medial tilt, and internal rotation during mid-stance phase. While FFS running reduces peak stress and strain in the patellar cartilage, it does not alter the fundamental stress distribution pattern or patellar movement. This suggests inherent spatiotemporal loading characteristics independent of foot strike pattern. Future prevention strategies should consider both the magnitude and spatiotemporal distribution of stress for more targeted interventions.