J Am Acad Orthop Surg, Vol 18, No 9, September 2010 John S. Kirkpatrick, MD, Charles N. Cornell, MD, Bang H. Hoang, MD, Wellington Hsu, MD, J. Tracy Watson, MD, William C. Watters, III, MD, Charles M. Turkelson, PhD, Janet L. Wies, MPH and Sara Anderson, MPH For this technology overview, the tools of evidence-based medicine were used to summarize information on the effectiveness and clinical outcomes related to the usage of bone void fillers specifically, synthetic graft materials. Comprehensive literature searches were conducted to address five key questions, which the task force that prepared the report posed as follows. Question 1 addressed the use of synthetic bone void fillers alone. Question 2 was designed to determine whether synthetic bone void fillers could successfully serve as graft extenders and eliminate the need for iliac crest bone graft. Questions 3, 4, and 5 addressed the use of allografts as a comparison with synthetic fillers because clinical results with allografts are perceived as being much closer to autografts in these areas of the spine.