Biomechanical validation of the solitary lag screw technique for reducing mandibular angle fractures

The purpose of this study was to determine whether the solitary lag screw technique meets the biomechanical demands of angle fractures. Simulated angle fractures in four cadaveric mandibles were reduced using solitary lag screws and the load-displacement relationships determined under functional loading of the individual mandibles. Subsequently, an angle fracture in a photoelastic mandible analog was fixed with a lag screw and subjected to similar loading. The mechanisms by which the solitary lag screw transferred functional loading were observed and recorded in a circular polariscope. Concomitant distraction tendencies were monitored and measured using displacement transducers. Correlation of the force-displacement measurements to photoelastic observation substantiated that the solitary lag screw functions as a tension band to provide a sufficient degree of interfragmentary compression and stability to withstand functional loading of the mandible.