A Robot Assisted Hip Fracture Reduction with a Navigation System

Sanghyun Joung, Hirokazu Kamon, Hongen Liao, Junichiro Iwaki, Touji Nakazawa, Mamoru Mitsuishi, Yoshikazu Nakajima, Tsuyoshi Koyama, Nobuhiko Sugano, Yuki Maeda, Masahiko Bessho, Satoru Ohashi, Takuya Matsumoto, Isao Ohnishi, Ichiro Sakuma

Abstract: A fracture reduction robot is described as assisting in safe and precise fracture reduction. The robot is connected with pins that are inserted into the patient’s bone fragments, together with a customized jig. The robot has six degrees of freedom with high precision, so that precise fracture reduction can be conducted. The failsafe unit of the fracture reduction robot can mitigate excessive reduction force that may cause complications such as avascular necrosis. We have integrated the fracture reduction robot with a navigation system that tracks the relative position of the bone fragments and generates the reduction path. The integrated system is evaluated with the simulated fracture reduction of a hip fracture model (n=8). Three-dimensional parameters related to the mechanical axis-the proximal femur angle, the distal femur angle, and the length of the mechanical axis-were evaluated by comparing the normal values with those after reduction; these average differences are 1.76°, 0.28° and 0.76mm, respectively. The automated fracture reduction feature makes it possible for medical staff to work at a distance from radiation sources; for patients, the integrated fracture reduction system has the potential to reduce fractures with high precision.