Validating a Novel 3D Printed Depth Gauge With Mandible Models

Background/needTraditional bone depth gauges are notoriously inaccurate tools, often used in head and neck surgery, that estimate the screw length needed for fracture fixation after bicortical drilling. Complications related to inaccurately sized screws may include soft tissue irritation or weakness of the repair and subsequent refracture. To improve size selection accuracy, a prototype depth gauge was 3D printed and tested in mandibles.MethodsThe prototype was constructed with a rotating deployable hook and intra-operative disassembly feature to extract the device if it became stuck. Ten 3.2 mm holes were drilled in a synthetic mandible, and 12 medical students, 12 residents, and 6 fellows/attendings measured them with industry standard and prototype depth gauges. User measurements from the prototype were compared to the holes' true depths and accuracy for each device was based on a user's closeness to the true depths. Differences between devices and training levels were analyzed with paired t tests and two-way ANOVAs. The device was also tested by 2 attendings in 2 cadavers with 8 holes drilled in each mandible.ResultsIn the synthetic model, differences between true depths and measured depths for the 2 gauges were not significantly different. Total accuracy was greater with the prototype, along with increased medical student accuracy compared to the industry standard. Prototype malfunctions were noted in the cadaveric model with no significant differences in device accuracy.ConclusionA novel 3D-printed depth gauge was tested and found to improve first time user accuracy and perform non-inferiorly to an industry standard depth gauge.