1. Shriners Hospital, 950 West Faris Road, Greenville, South Carolina 29605, USA.
2. University of South Carolina, 2 Medical Park, Site 404, Columbia, South Carolina 29203, USA
3. Department of Orthopaedic Surgery, Greenville Hospital System University, Medical Centre, 701 Grove Road, 2nd Floor Support Tower, Greenville, South Carolina 29605, USA.
4. Department of Epidemiology and Biostatistics, University of South Carolina, 800 Sumter Street, Columbia, South Carolina 29208, USA.