The Principal aim of the present research is to compare two methods of antibiotic delivery: concomitant TAD and IVAD versus IVAD alone (TAD+IVAD vs IVAD) with respect to the prevention of surgical site infections (SSI). The secondary aim of this study is to compare TAD+IVAD vs IVAD with respect to the prevention of post-operative venous thromboembolism (VTE). This research is an open label randomized clinical trial (RCT) comparing two modes of antibiotic delivery. It is not a trial comparing antibiotics.