229 patients undergoing open reduction and internal fixation (ORIF) of a closed limb fracture, with standard preoperative and intraoperative prophylactic antibiotic administration, were randomized to receive 23 hours of postoperative prophylactic cefazolin or placebo. The primary purpose of this trial was to compare infection rates between these two postoperative treatments until bony union. Results found postoperative cefazolin did not significantly reduce the incidence of infection compared to placebo. Furthermore, diabetes and surgery exceeding 3 hours were recognized a risk factors that increased the rate of infection.