Measurement of traction load and torque transferred to the lower extremity during simulated fracture reduction

Abstract

The reduction of hip fracture depends on the surgeons' experiments and subjects. Poor fracture reduction often leads to clinical failure. We have developed robotic surgical assistants to provide safe and accurate fracture reduction and adequate process calculated by computer. In order to develop such robots, it is necessary to define the medical safe range of motion and loading in human subjects. To establish these parameters, we measured forces and torques applied to the lower limb during simulated fracture reduction. 62 healthy and young volunteers were included in this study. According to the conventional reduction process, the volunteers' limbs were tracted and then rotated. Force of traction and torque of rotation were measured by a force sensor (Nitta Corporation, Japan). The maximum traction force applied to the lower limbs was averaged 232.9 N, and the maximum torques were 6.31 N m in external rotation and 7.69 N m in internal rotation. These values in males were larger than those in females. During the reduction process, the traction forces were gradually increasing, whereas the torques of rotation was sharply increasing after maximum range of hip rotation was reached. This data will be useful for the development of safe robotic surgical assistants for fracture reduction.