1. Orthopaedics Biomechanics Laboratory, Department of Orthopaedics and Rehabilitation, University of Iowa, 2181 Westlawn, Iowa City, Iowa 52242-1100, USA, Section of Orthopaedic Surgery, University of Kansas Medical Center, 5002 Eaton Hall, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, USA, Department of Orthopaedics and Rehabilitation University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242-1088, USA.