Following medical school he continued his surgical training in Hamburg, Philadelphia, Annaba, Algeria, (Mission Chirurgicale de la République Fédérale d' Allemagne) to become Board certified General Surgeon and after an additional two years, a Board certified Unfallchirurg (surgeon for soft tissue, visceral and orthopedic trauma).In 1988, after organizing an International Congress in Hamburg, Germany, with the sole topic of intra-abdominal infection and founding the Surgical Infection Society - Europe, he accepted a position as professor of surgery at the Medical College of Wisconsin.
Based on these studies Wittmann habilitated for professor of surgery at the University of Hamburg defending his thesis about the concentration dynamics of antimicrobials intra-abdominal infections.
The culmination of experiences led Wittmann to begin to develop a means to keep the abdominal wall safely open for serial intra-operative treatment and control of healing processes.
In 2000 Wittmann retired from the medical college but continued his work on the staged abdominal repair and the hook and loop fastener temporary fascia prosthesis.
Eur J Surg 159: 75-79, 1993 414 Staged abdominal repair: Development and current practice of an advanced operative technique for diffuse suppurative peritonitis by Dietmar H. Wittmann.