1. Department of Physical Medicine and Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA, USA
2. Department of Rehabilitation and Aged Care, Repatriation General Hospital, Adelaide, Australia
3. Department of Physical Medicine and Rehabilitation, University of Catania, Catania, Italy
4. Istituto Ortopedico Rizzoli, University of Bologna, Italy
5. Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA