The overall goal of this clinical study is to characterize the fusion rate of geneX® ds bone graft substitute in comparison to autograft, which is considered the gold standard for posterolateral fusion. Assessments are made using AP and Lateral x-rays, F/E x-rays, and CT scans geneX® ds has been cleared by the FDA for use in these procedures; however this study will allow more detailed characterization of geneX® ds performance in the long-term (1 year). By using the patient as their own control, direct comparison to autograft can be performed while minimizing other variables.