1. Department of Medicine, Michael G DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
2. Department of Orthopaedic Surgery, McMaster University, Hamilton, Ontario, Canada
3. Department of Medicine, University of Toronto, Toronto, Ontario, Canada
4. Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
5. Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania