Total hip replacement is a surgery that change damaged hip joint by implant when hip joint was damaged by osteoarthritis or accident, etc. In manual surgery, bone fracture, misalignment and positioning of implant affect to result of surgery. To do solve these problems, some robot systems for total hip replacement have suggested and developed. In robot surgery, no fracture was found and alignment and positioning of implant was improved. But, disadvantages of robot surgery were higher dislocation rate. It is expected that the amount of muscle damage in robot surgery was responsible for the higher dislocation rate. So, development of robot that can decrease incision is needed.
In this study, we developed robot for total hip replacement. To decrease incision during surgery, robot is fixed to femur using bone cavity. In design process, we suggested required performance of robot. Considering required performance, four kinds of candidates were suggested and selected one by decision matrix. After detailed design, we made robot system. To test robot performance, we did experiments using plastic bone. During cutting plastic bone we measured time. After cutting bone, plastic implant were inserted to measure fit rate of bone and implant. The cutting time was longer than other robot surgery systems and fit rate was similar. And alignment of implant was indicated. It is needed to improve proposed system to apply in surgery.