Biomechanical assessment of a novel lengthening plate for distraction osteogenesis: A finite element study

Purpose: The purpose of this study was to describe a novel bone lengthening plate (BLP) and to evaluate the biomechanical performance of the plate before clinical use. Methods: A finite element model was obtained from values of the compression test. It was used to evaluate the performance of the BLP, such as biomechanical stability and structural stiffness, according to materials of the shaft and column used for lengthening (type I: all Titanium-alloys, type II and III: Titanium-alloys and Cobalt-Chrome-alloys, type IV: all Cobalt-Chrome-alloys). Furthermore, Peak von Mises Stress, risk of screw breakage, and micro-motion between the bone and screw were evaluated. Results: Structural stiffness and strain of the finite element model of the femur were similar to cadaveric femurs. Structural stiffness increased from type I (Titanium alloys) to type IV (Cobalt-Chrome-alloys) by at least 128%. First locking screw, which was inserted at the osteotomy site of the proximal femur (proximal to distal direction), showed the highest risk of breakage (75%). Conclusions: This study investigated biomechanical stability of the novel BLP in relation to properties of the supporting structures. It was most biomechanically stable when the column and lengthening shaft were composed of Cobalt-Chrome-alloys (type IV).