Abstract:

BACKGROUND: Finite element modeling in biomechanical experiment has advantages in shorter experiment time, lower expense, simulation of complex boundary condition, full analysis of biomechanical characteristics and repeatability.
OBJECTIVE: To establish a finite element model of ankle arthrodesis with fibular strut graft, to evaluate the biomechanical stability and safety, and to study the biomechanical characteristics of ankle arthrodesis with fibular strut graft.
METHODS: A three-dimensional model of a healthy ankle was developed from computed tomography images. Ankle arthrodesis was simulated by Abaqus 6.9 software, and the model was submitted to mechanical analysis under four load procedures according to the postoperative activity pattern of ankle (neutral position, dorsiflexion, external rotation and internal rotation).
RESULTS AND CONCLUSION: The model was successful established and had high geometric similarity. In dorsiflexion status, posterior-anterior screw yielded maximum stress concentration at middle part; meanwhile, maximum displacement occurred at the fusion site. Screw stress at posterolateral tibial was maximal. A high concentrated stress was found surrounding the screw hole. High stress was distributed between the screw holes of fibular strut. To avoid the high concentration of stress distribution, the crossed screws should be configured appropriately. And additional ante-dorsiflexion immobilization might lower the risk of screw implant failure. Shortening of distance between parallel screws and centralized drilling on fibula also tended to reduce the risk of strut failure.