A bending model for assessing relative stiffness and strength of orthopaedic fixation constructs

Abstract

BackgroundThe purpose of this study is to develop a simple and reproducible bending model that is compatible with a wide range of orthopaedic fixation devices and 3D printed spacers. MethodsA robust 4-point bending model was constructed by securing sawbones blocks with different orthopaedic fixation device constructs. Stress strain curves derived from a fundamental mechanics model were used to assess the effect of bone density, type of hardware (staple vs intramedullary beam), the use of dynamic compression, orientation of staples (dorsal vs plantar), and the use of 3D printed titanium spacers. FindingsThe high throughput 4-point bending model is simple enough that the methods can be easily repeated to assess a wide range of fixation methods, while complex enough to provide clinically relevant information. InterpretationsIt is recommended that this model is used to assess a large initial set of fixation methods in direct and straightforward comparisons.