Accuracy Evaluation of a Drill Guidance System for Orthopaedic Surgery

When placing a screw or wire (K-wire) into bone orthopaedic surgeons attempt to make the first drill pass the only drill pass. This is difficult, however, as they are dealing with complex 3-dimensional shapes with limited
access due to the soft tissues. In current practice intra-operative fluoroscopy is used to assist the surgeon but this is limited to 2-dimensional images for the majority of Operating Rooms (OR). This results in multiple attempts in order to achieve optimal positioning, making the process time-consuming and potentially damaging to the soft tissue and bone, resulting in excessive removal of material from the bone, as well exposing the OR staff to increased doses of radiation. Although there are existing tracking methods using optical or forced-based techniques these are time-consuming to setup, suffer from occlusions or lowered precision depending on conditions. This paper documents the initial development of a Drill Guidance System (DGS) to help surgeons
drill into bones, especially smaller ones, accurately at the first attempt using a localised vision-based approach. The proposed system can be used easily retrofitted to existing drilling equipment and, being localised to the surgical field, is not prone to accidental occlusions during operation. We are presenting original laboratory results which demonstrate that for usable drilling distances for screw/wire placements of 300mm and 400mm, accuracies of 0.45+-0.56mm and 0.391.2mm respectively can be achieved which is safely below the desired accuracy of 2mm as set by discussions with surgeons.