Digital volume correlation of bone-screw interface at different tightening levels

Stripping during screw insertion occurs with an incidence as high as 50% [1]. With an increase in age and osteoporosis, overtightening is more likely as surgeons try to achieve torques similar to that observed in young healthy bone. Stripping torque can be predicted based on the torque at head contact[2]. The question remains however, “how tight is tight enough?”. Due to the diffusion of in situ biomechanical imaging (mainly via micro-CT), digital volume correlation (DVC) has become a powerful tool to measure full-field internal deformations in trabecular/cortical bone [3] and bone-biomaterial systems [4]. This ongoing study uses a custom developed computer-controlled screw insertion device to perform time-elapsed micro-CT imaging of the bone-implant interface, in combination with DVC. The aim is to quantify the deformation of the trabecular bone at each rotation step with increased tightening torque.