Accurate femoral canal shaping in total hip arthroplasty using a mini-robot

We propose a greatly simplified femoral canal shaping method for robot-assisted total hip replacement surgery that requires neither CT/MRI imaging nor insertion of fiducial markers before surgery. A reamer-shaped registration gauge is inserted into the femoral canal and used to position a base for a robot that is mounted on the top of the femur and used to prepare the femoral canal. In a study using 5 fresh cadavers, the average registration error for selected points near the surface of the femoral cavity was 0.59 mm; this is comparable to the errors reported for the geometry-based registration methods.