1. Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, USA
2. Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, USA
3. Department of Physical Therapy, University of Delaware, Newark, USA
4. Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, USA
5. Department of Organizational Systems and Adult Health, University of Maryland School of Nursing, Baltimore, USA
6. Department of Orthopedics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA