Investigation of a novel implant design for the treatment of reverse oblique femoral intertrochanteric fractures

Objective: To evaluate the biomechanical properties of intramedullary fixation, lateral plate, medial buttress plate and bilateral plate for fixing reverse oblique intertrochanteric fractures. Methods: Twenty-four synthetic femoral bone models (Synbone) were divided into four groups [proximal femoral nail anti-rotation (PFNA), proximal femoral medial buttress plate (PFMBP), proximal femoral locking compression plate (PFLCP) and proximal femoral medial buttress plate + proximal femoral locking compression plate (PFMBL+PFLCP)], and an unstable, reverse oblique femoral intertrochanteric fracture was made. After fixation, each model underwent axial load testing, torsion testing, and axial load-to-failure testing. The stiffness of axial and torsion, the torque of different torsion angles and the failure load of every model were recorded. Results: The bilateral plate showed the best performance in axial load, torsion, and load-to-failure testing. The stiffness of axial and torsion in the PFMBP was superior to the PFNA [162.05±22.05 N/mm vs. 119.13±29.14 N/mm in axial, (1.36±0.32) N × mm/deg vs. (1.10±0.13) N × mm/deg in torsion, P<0.05], whereas there was no significant difference between PFMBP, PFLCP and PFLCP+PFMBP in torsion stiffness [(1.36±0.32) N × mm/deg, (1.45±0.44) N × mm/deg, (1.45±0.18) N × mm/deg, P>0.05]. Conclusion: Our newly designed medial buttress plate achieved greater stiffness in axial load and torsion than PFNA and PFLCP to fix reverse oblique intertrochanteric fractures in biomechanical research, whereas the bilateral plate showed better stiffness than PFMBP.