The objective of this study was to determine the fifth metatarsal strain generation mechanism during cutting motions performed while playing soccer using a finite element foot model. Five collegiate soccer players performed the side-step cutting and the cross-step cutting motions to measure the three-dimensional foot kinematics, ground reaction force, and plantar pressure distribution. In addition, a finite-element model of a foot consisting of bony structures, ligaments, and skin was constructed from computed tomography images. Simulations were conducted to perform the cutting motions, using the measured foot motion and distributed load on the plantar surface as boundary conditions for the model. During the side-step cutting, the maximum principal strain on the fifth metatarsal was correlated to forefoot adduction angle during stepping out. For cross-step cutting, the maximum principal strain was correlated with plantar pressure at the distal end of the fifth metatarsal. Therefore, to prevent a fracture, it is necessary to take measures to reduce the lateral bending deformation of the forefoot while stepping out during side-step cutting and to reduce the plantar pressure on the distal end of the fifth metatarsal during cross-step cutting.
Keywords: Fifth metatarsal stress fracture; finite-element foot model; plantar pressure distribution; soccer.