Objective To investigate the effects of sand therapy temperature on bone reconstruction and numerical study on the heat transfer.Methods CT scan imaging was performed respectively for four times(before and after OA model was set up,and after the first and second weeks during the sand therapy).Import the scan data to MIMICS software,and the changes of femoral bone mass layer were analyzed.After combining the muscle,femur,bone marrow and meshing,the established three-dimensional model of the STL format was introduced into the COMSOL software for heat transfer simulation and effect of stress on bone remodeling induced by temperature field.Results Changes of four CT scan data were analyzed.The soft bone volume was reduced,while the dense and hard bone volume were increased.Numerical simulation on the heat transfer showed the temperature distribution of the thigh and the femur.Conclusions The thermal stress produced by sand therapy temperature exert promoting effect on the femur bone remodeling.

BACKGROUND:The injury of the anterior talofibular ligament is most common in joint ligament injuries.The use of the finite element method to simulate ankle joint motion has the advantages of short experimental time,complex boundary conditions that can be simulated,and mechanical properties. OBJECTIVE:To analyze the effect of the anterior talofibular ligament on the stress distribution of the talus trochlea and the stability of the ankle joint. METHODS:A finite element model of the ankle was established based on CT and MRI images of patients with anterior talofibular ligament injury who were followed up for two months after Brostr?m surgery to simulate ankle joint stress in patients with anterior talofibular ligament injury before and after surgery during normal gait cycles(ground phase,neutral phase,and off-ground phase).The stress distribution and maximum stress value of the talus bone cartilage were measured before and after surgery,and their differences were analyzed. RESULTS AND CONCLUSION:Under normal gait,the anterior talofibular ligament has a certain protective effect on the talus trochlea in any position,reducing the wear of the ankle joint on the talus trochlea during movement.In all three phases,stress concentration was observed on the surface of the talus trochlea near the inner side of the ankle joint.The influence of the anterior talofibular ligament on the stability of the talus trochlear is much greater in the off-ground phase than in the ground phase and neutral phase.Under certain circumstances,the greater the torque on the ankle joint,the more significant the effect of the anterior talofibular ligament on the stability of the talus trochlea.