An experimental model to measure the torque of pin insertion and extraction for external fixation

An original system used to measure torque of pin insertion and extraction in external fixation is presented. The system is made up of an electronic dynamometric key and an analogic/digital switchboard that may be linked up to a personal computer. The in vitro results show the simplicity of use and the versatility of the system, that is capable of providing the surgeon with accurate indicative values as to the mechanical resistance of the bone-pin interface during implantation of any fixator.