1. Department of Orthopaedics and Rehabilitation, University of Iowa Hospitals and Clinics, Iowa City, USA
2. Innovation Laboratory, Signal Center, University of Iowa Hospitals and Clinics, Iowa City, USA
3. Steindler Orthopaedic Clinic, Iowa City, IA, USA
4. Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, USA
5. Department of Orthopaedic Surgery, Northwestern University, Chicago, USA