This is a multicenter randomized controlled, postmarket clinical study to determine the differences between subjects undergoing standard MLF surgery with S2AI fixation in the pelvis vs the additional placement of iFuse 3-D in the bedrock configuration during MLF surgery. Subjects will be monitored for sacroiliac (SI) joint pain and at two years post surgery a CT scan will be taken to assess S2AI screw loosening or any other findings.
The purpose of this study is to compare outcomes of subjects undergoing multilevel lumbar fusion (MLF) surgery with and without the iFuse 3-D implants in the bedrock trajectory.