Intramedullary pin fixation in 3D printed canine femur bone model for preoperative surgical planning

The majority of complications associated with internal fixations in treating long bone fractures are due to a lack of preoperative surgical planning and decision making. The computer-assisted preoperative surgical planning in conjunction with 3D printing can limit these complications. For improving the surgeon's understanding of the patient case by preoperative surgical planning, this study presents insight on parametric optimization of modulus of toughness (MOT) for pull-out strength of intramedullary pin (IM) fixation of the canine femur bone fracture as a novel solution (in place of commercially used cadaver specimens). In this study coupled loading approach (tensile and impact) was used by considering detachment rate (mm/min), the number of threads engaged, and the angle of insertion in a 3D printed canine femur bone anatomical model. The parametric optimization was performed based upon the design of the experiment to determine the holding power of the implant in terms of mechanical strength and fracture of screw tapping in bone through reverse engineering for fixation of femoral fracture. The results highlight that the IM pin inserted at an angle of 2.5°, with 8 engaged threads, has better mechanical properties in terms of MOT. Results are supported by surface properties of the fractured zone by scanning electron microscopy, porosity, surface roughness (Ra), amplitude distribution function, peak count, and bearing ratio curve analysis. (author)