1. Physical Therapy Division , Department of Orthopaedic Surgery, , Durham, North Carolina, USA
2. Duke University School of Medicine , Department of Orthopaedic Surgery, , Durham, North Carolina, USA
3. Physical Therapy Program , School of Medicine, , Aurora, Colorado, USA
4. University of Colorado , School of Medicine, , Aurora, Colorado, USA
5. Division of Physical Therapy, University of Minnesota , Minneapolis, Minnesota, USA