Dr. Maddox completed his medical degree from the University of Arkansas for Medical Sciences in 1991. He completed his residency training in Emergency Medicine from UAMS in 1995. After residency, he worked for several years in private practice at a small community-based hospital located in Arkansas. He remained on staff at UAMS as a part-time clinical attending during this period. His interest in the business of Emergency Medicine led him to become the Medical Director, member of the Board of Directors, and Chief of Staff. With his continued love of teaching, he rejoined the faculty full-time as an Assistant Professor of Emergency Medicine in 2007. Shortly after joining the department, he was named the Medical Director. Currently, he is the department's interim chair and service line director. He was promoted to Professor in 2020.

Dr. Maddox has been actively involved in many medical organizations, including the American College of Emergency Physicians, and has served as the President of the Arkansas Chapter. He remains on the Board of Directors of that organization. He is on the Board of Trustees for the Arkansas Medical Society, UAMS Hospital Medical Board, and numerous other committees that support UAMS. He was named UAMS Physician of the Year for clinical excellence in 2022. Dr. Maddox has received the Robert A. Fisher Excellence in Teaching Award in 2008, 2009, and 2010. Through his research projects with residents, he has developed areas of continued education for residents training in emergency medicine. These areas include the recognition of x-ray, EKG, and physical findings associated with emergency conditions. Dr. Maddox's research interest consists of evaluating missed injuries that occur during managing the trauma patient at a level 1 trauma center. Other areas of particular interest also include the medical-legal aspects of Emergency Medicine, EMTALA, care and management of the difficult airway, trauma, and pregnancy, and the business of emergency medicine. He has developed hospital protocols for the treatment of both sepsis and pneumonia.