Development of a Biomechanical Model Producing Proximal Pedicle Pullout of Long Fusion Spinal Constructs

Proximal pedicle screw pullout is a common clinical occurrence for long fusion constructs. Recently, novel spinal hardware and surgical techniques have been in development to alleviate this complication [1]. However, there is currently no biomechanical model to simulate this mode of failure in vitro to adequately evaluate these strategies in a rigorous laboratory setting. Standard pure moment loading and range of motion testing are not equipped to reproduce this failure modality [2] and a vast majority of such outcomes have merely been observed clinically [3]. It is hypothesized that a combination of anterior-posterior (AP) shear and compressive force is required to induce screw pullout with clinically similar fatigue patterns. The goal of this preliminary study is the development of such a biomechanical model to simulate clinically observed proximal pedicle screw failure.