Biomechanical and Histological Evaluation of an Allograft Anchor for Pedicle Screw Augmentation in an Ovine Model

INTRODUCTION Achieving solid implant fixation to osteoporotic bone presents a challenge to both spinal surgeons and hardware designers. Loss of surgical construct stability as a result of screw loosening is a well-known complication [1,2], particularly in patients with poor bone quality [3,4]. Thus, the development of novel strategies to address the issue of obtaining enhanced bone-to-screw purchase to achieve necessary construct integrity is an important issue. In the current work, we investigated the effect of lumbar pedicle screws augmented with a bone allograft anchor in an ovine model with temporal biomechanical testing and histological analyses. We hypothesized that the allograft sheath would be gradually incorporated by the host, thereby promoting enhanced pedicle screw purchase.