Novel method to evaluate femoral head penetration in the polyethylene liner after total hip arthroplasty: three-dimensional evaluation on standing radiographs

Background After total hip arthroplasty, the femoral head penetrates the liner because of polyethylene wear and the so-called bedding-in phenomenon. The head moves three-dimensionally, but few reports have evaluated such movement radiographically. Moreover, even fewer reports have evaluated it in a standing position, although the load stress influences the movement. The purpose of the present study was to evaluate the head movement in the liner three-dimensionally using standing images.