He received his bachelor's degree from Carroll College in 1979 and his medical doctor degree from the University of Wisconsin-Madison in 1983. In 1986, Dr. Erdmann completed his residency in Internal Medicine at the Medical College of Wisconsin. Dr. Erdmann holds a board certification in Internal Medicine. In 1989, he received his master's degree from the University of Michigan, School of Public Health.

The Milwaukee VA Medical Center is closely affiliated with the Medical College of Wisconsin where Dr. Erdmann serves as associate dean for VA Affairs and professor of medicine, Division of General Internal Medicine. Prior to becoming Chief of Staff, Dr. Erdmann served as Chief, Medical Service, Milwaukee VAMC and Vice Chairman, Department of Medicine at the Medical College of Wisconsin.

Dr. Erdmann oversees the provision of tertiary care clinical services at the Milwaukee VA Medical Center. The institution offers expertise in cardio-vascular care, spinal cord injuries, medical, surgical and radiation oncology, all medical and surgical subspecialties, mental health and rehabilitation and geriatrics. Milwaukee is a front runner in telemedicine including offering telemental health, telepathology, telepulmonary, teledermatology, telepost operative evaluations, teleradiology (including ultrasound and fluoroscopy) and telehome-health care. Dr. Erdmann provides clinical leadership to Milwaukee's community based outpatient clinics in Union Grove, Appleton, Green Bay, and Cleveland, WI.

Dr. Erdmann is active in his community schools, government and church. Hobbies include running, outdoor activities and viewing Wisconsin’s professional and college sports.