1. Department of Orthopaedic Surgery, Walter Reed National Military Medical Center , Bethesda, MD 20889, USA
2. Department of Orthopaedic Surgery, Uniformed Services University of the Health Sciences , Bethesda, MD 20814, USA
3. Department of Orthopaedic Surgery, Duke University Medical Center , Durham, NC 27710, USA
4. Department of Orthopaedic Surgery, Vanderbilt University Medical Center , Nashville, TN 37232, USA