607 patients with spondylolisthesis were separated into two cohorts. The first cohort was a randomized cohort, where patients were randomized to either operative or non-operative care. The second cohort was comprised of patients unwilling to undergo randomization. These patients chose to either undergo operative or non-operative care. Adherence to the treatment groups in both cohorts was low, with a significant number of non-operative patients electing to undergo surgery. As-treated analysis demonstrated significant improvements in pain and function scores at 4 year follow-up in the operative groups in both cohorts.