[1] Orthopaedic and Rehabilitation Engineering Center, Marquette University, Milwaukee,WI, United States
[2] Department of Orthopaedic Surgery, Medical College of Wisconsin, Milwaukee,WI, United States
[3] Shriners Hospital for Children, Chicago,IL, United States
[4] Physical Therapy Program, Midwestern University, Downers Grove,IL, United States
[5] Department of Biostatistics, Medical College of Wisconsin, Milwaukee,WI, United States