Design of an Electric Hexapod External Fixator System and Fracture Reduction Method

doi:10.3901/JME.2025.17.205

Abstract

Abstract: The hexapod external fixator is widely used in the treatment of fractures and the correction of skeletal deformities. Synchronized electrical adjustment of its six connecting rods proves advantageous in preventing harmful shear stresses, while measurement of mechanical load-sharing ratios enables monitoring of skeletal growth and healing progress, thereby avoiding bone-end stress shielding to facilitate recovery. An electromechanical hexapod external fixator system is accordingly developed, comprising three primary components: a structural frame, control module, and human-machine interface. An electromechanical structure incorporating built-in motors and pressure sensors is designed to enable automatic rod-length adjustment through control module operation and real-time force monitoring. A mathematical model of the fixator is established, and the fracture reduction algorithm and the calculation method for the axial load-sharing ratio of the fixator are derived, permitting determination of repositioning parameters and load distribution under various installation configurations and deformity conditions. A fixator-fracture simulation model is established to verify the correctness of the fracture reduction algorithm. A femoral fracture reduction experiment is conducted, and the results show that the electric hexapod external fixator system can effectively achieve fracture reduction and monitoring of the fixator’s force.

Key words: external fixator, electric actuator rods, fracture reduction, bone end force

CLC Number:

TH89

DU Jiajia, LI Xinghua, ZHANG Tao, LIU Zhao, MEI Xiaolong, LI Shaohui, XU Weiguo. Design of an Electric Hexapod External Fixator System and Fracture Reduction Method[J]. Journal of Mechanical Engineering, 2025, 61(17): 205-214.

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