Affiliations: [a] Department of Trauma Surgery, Hannover Medical School, Hannover, Germany | [b] Institute for Robotics and Process Control, Technical University of Braunschweig, Braunschweig, Germany | [c] Department of Orthopaedic Surgery and Sports Medicine, University of Washington, Harborview Medical Center, Seattle, WA, USA
Correspondence:
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Address for correspondence: Markus Oszwald, Department of Trauma Surgery, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany. E-mail: oszwald.markus@mh-hannover.de.
Abstract: Introduction:The insertion site for an antegrade femoral intramedullary nail in the treatment of a femoral shaft fracture has traditionally been performed using a free-hand technique. An inappropriate starting point can result in suboptimal nail insertion leading to malreduction, or iatrogenic fracture. Furthermore, repeated attempts to establishthe optimal starting point cancause additional soft tissue trauma and radiation exposure. In the following study we compared a robot-guided technique with the standard free-hand technique for establishing the entry point of an antegrade femoral nail. We hypothesized that the robot-guided technique is more reliable and efficient. Methods:A custom-made drill-guide was mounted onto the arm of an industrial robot. Two orthogonal fluoroscopic images were acquired from the proximal femur of five cadaveric human specimens. Images were processed with a specialsoftwarein order to create an enhanced contour-recognition map from which the bone axes were automatically calculated. The drilling trajectory was computed along the extension of the bone-axis. The robot then moved the drill-guide on this trajectory toward the entry point. The drilling was then performed by the surgeon. In the control group, five cadaveric human femora were utilized to manually establish the starting pointusing the free-hand technique. Results:100% of the intramedullary cavities were successfully accessed with both the robot-guided and the manual techniques. In the manual technique repositioning of the drill was necessary in three out of five cases. The mean number of acquired fluoroscopic images was significantly reduced from 11.6 (manual) to 4 (robot-guided). Conclusion:Robot-assisted drilling ofthe entry-point in antegrade femoral nailingis more reliable and requires fewer radiographic images than the free hand technique. Yet, based on economical and logistical considerations, its application will probably only be accepted when a concomitant application for fracture reduction is available.
