Three-dimensional Photoelastic Test and Mechanism Analysis of Calcaneal Fracture

Objective:To study the biomechanical features of calcaneus with three-dimensional photoelastic method and analyze the mechanism of calcaneal fracture.Methods:The left leg with the foot of an adult man was dissected for theoretical mechanics analysis.A calcaneus model of epoxy resin was made under freezing-stress and then the slices were submitted to photoelastic system.Results:The results showed that the stress value of the calcaneus increased significantly and concentrated largely upward and forward when the ankle was in the position of dorsiflexion 15 degrees than it was in the neutral position.The high stress concentration zone were around the calcaneocuboid joint,calcaneal cumulus,areas around calcaneal Gissane's angle,posterior subtalar joint and the tibial side of calcaneal tubercle which directly touches the ground when falling.Conclusions:①When falling from the same height while calcaneus touching the ground,it is more likely to cause calcaneus fracture with the ankle in the position of dorsiflexion 15 degrees rather than in the neutral position.②The stress concentration trend which appears when landing at the ankle dorsiflexion position of 15 degrees will easily result in fractures of calcaneocuboid joint and Y-type comminuted fracture of posterior subtalar joint.