1. Department of Physical Medicine and Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD 20889, USA
2. Department of Physical Medicine and Rehabilitation, Uniformed Services University, Bethesda, MD 20814, USA
3. Section of Orthopedics, Veteran Affairs Medical Center, Washington, DC 20422, USA
4. Pathology and Laboratory Medicine Service, Veteran Affairs Medical Center, Washington, DC 20422, USA
5. Department of Pathology, The George Washington University, Washington, DC 20037, USA
6. Martin Health, Greenbelt, MD 20770, USA