This is a single-center, prospective, randomized study. Subjects will be recruited from patients already under the Investigator's care who are indicated for XLIF with iliac crest bone graft (ICBG) autograft or AttraX Putty. To minimize bias, all consecutive patients at a given investigational site who meet eligibility requirements will be asked to consent to participate in the study whereby the biologic (ICBG autograft or AttraX Putty) will be randomly assigned. All subjects will be followed for 24 months following surgery to quantify the clinical and radiographic improvements of each biologic compared to baseline and in comparison with each other.