1. Department of Rehabilitation Medicine, University of Tsukuba hospital, Tsukuba 305-8576, Japan
2. Doctoral Program in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba 305-8575, Japan
3. Department of Rehabilitation Medicine, Institute of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan
4. Department of Orthopedic Surgery, Institute of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan