He specializes in trauma care and limb amputation. William Ertl, MD, is an assistant professor in the College of Medicine, Department of Orthopedic Surgery and Rehabilitation, at the University of Oklahoma Health Science Center, Oklahoma City, Oklahoma. Christian Ertl, MD, FACS, is a community surgeon and clinical instructor in the Department of Surgery at the University of Connecticut, Bristol. He specializes in general surgery, including limb amputation.