Biomechanical analysis of suture locations of the distal plantar fascia in partial foot

Purpose: The aim of this study was to evaluate the rationality of the suture locations of distal plantar fascia (DPF) after foot amputation to avoid the risk factors of re-amputation or plantar fasciitis. Methods: The tensile strain of plantar fascia (PF) in the different regions was measured by uni-axial tensile experiment. A three-dimensional (3D) finite element model was also developed to simulate tensile behaviour of PF in weight bearing conditions. The model includes 12 bones, ligaments, PF, cartilage and soft tissues. Four suture location models for the DPF were considered: the fourth and fifth DPF were sutured on the third metatarsal, the cuboid, and both the third metatarsal and the cuboid, and one un-sutured model. Results: The peak tensile strain of the first, second and third PF was 0.134, 0.128 and 0.138 based on the mechanical test, respectively. The fourth and fifth DPF sutured at the cuboid and the third metatarsal could offer more favourable outcomes. The peak strain of 4.859 × 10^–2, 2.347 × 10^–2 and 1.364 × 10^–2 in the first, second and third PF showed the least outcomes in stance phase. Also, peak strain and stress of the residual PF reduced to 4.859 × 10^–2 and 1.834 MPa, respectively. The stress region was redistributed on the mid-shaft of the first and third PF and the peak stress of medial cuneiform bone evidently decreased. Conclusions: The fourth and fifth DPF suture at the third metatarsal and cuboid was appropriate for the partial foot. The findings are expected to suggest optimal surgical plan of the DPF suture and guide further therapeutic planning of partial foot patients.