1Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA 15213
2Department of Biomedical Engineering, School of Medicine, Kitasato University, Kanagawa, Japan 228
3Mitsubishi Electric Corporation, Aichi, Japan 461
4Department of Orthopaedic Surgery, School of Medicine, Kitasato University, Kanagawa, Japan 228