Understanding the differences between a physician and a chiropractor and knowing key terms and billing codes will assist adjusters handling workers’ compensation claims, according to a recent webinar presented by Wisc.-based insurance broker HNI. According to Dr. Marc Gilerovich, a chiropractor and the HNI University webinar presenter, chiropractors need eight years of education - four years each of undergraduate and graduate school. In addition, they need to pass four national board examinations.