Initial validation of automatic torque-limiting bone screwdriver system

Abstract

Bone screw tightening torque is important to achieve the best patient outcomes in orthopedic procedures. Here, an automatic method was tested for determining the stripping torque of a screw during the initial insertion of the screw. This involved an inverse model to determine material strength, followed by a forward model to estimate stripping torque. This method was tested on 2 different densities of polyurethane foam as a substitute for real bone. It was found the model-identified/estimated strengths/torques closely followed the datasheet/measured values. This method shows promise for predicting stripping torque. However, further work is needed to better quantify the accuracy.