1. Department of Mechanical Engineering, University of Colorado Denver, Denver, CO, USA
2. Center for Bioengineering, University of Colorado Denver, Aurora, CO, USA
3. Department of Physical Medicine and Rehabilitation, University of Colorado School of Medicine, Aurora, CO, USA
4. VA Eastern Colorado Geriatric Research Education and Clinical Center, Aurora, CO, USA
5. Department of Orthopedics, University of Colorado School of Medicine, Aurora, CO, USA
6. University of Colorado Hospital, Aurora, CO, USA