Screw Torque and Bone Plate Fixation to Equine Cadaver Longbones

Abstract

SummaryThe purpose of the study was to determine what contribution an individual surgeon, their gender and the location of screw application within the bone makes to the perceived optimal applied screw torque (Mopt) for bone plate fixation to equine cadaver longbones. Five surgeons were required to apply a 4.5 mm broad dynamic compression plate, using 4.5 mm fully-threaded cortical bone screws, to the lateral diaphysis of an equine third metacarpal bone.Consideration of within (repetition) and between individual differences was significant (P = 0.010, P = 0.0001) as was gender (P = 0.0001) with male surgeons applying higher levels of torque. There did not appear to be a contribution to variability by location (P = 0.065). Regression analysis of Mopt and cortical thickness showed no linear relationship between these parameters (R2 = 0.088), allowing the conclusion that cortical thickness did not influence the perceived optimal applied screw torque.Screw torque was also measured at point-of-failure (Mmax) showing no relationship to location.This study examined the contribution of variation within and between individual surgeons, their gender and the location of screw application in the bone on the perceived optimal applied screw torque for bone plate fixation to equine cadaver longbones.Significant differences were seen within (repetition) and between individuals. When individuals were grouped according to gender significant differences also arose (males applying greater levels of torque than females). The results suggest, that for mature equine longbone fracture repair the use of a torque-limiting device may be a consideration in order to standardize bone plate fixation.