Pedicle Screw-Associated Violation of the Adjacent Unfused Facet Joint: Clinical Outcomes and Fusion Rates

Study Design: Retrospective review of a prospective randomized trial. Objectives: To compare outcome scores and fusion rates in patients with and without pedicle screw-associated facet joint violation (FJV) after a single-level lumbar fusion. Methods: Clinical outcomes data and computed tomography (CT) imaging were reviewed for 157 patients participating in a multicenter prospective trial. Post-operative CT scans at 12-months follow-up were examined for fusion status and FJV. Patient-reported outcomes (PROs) included Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) for leg and low back pain. Chi-square test of independence was used to compare proportions between groups on categorical measures. Two-sample t-test was used to identify differences in mean patient outcome scores. Logistic regression models were performed to determine association between FJV and fusion rates. Results: Of the 157 patients included, there were 18 (11.5%) with FJV (Group A) and 139 (88.5%) without FJV (Group B). Patients with FJV experienced less improvement in ODI (P =.004) and VAS back pain scores (P =.04) vs patients without FJV. There was no difference in mean VAS leg pain (P =.4997). The rate of fusion at 12-months for patients with FJV (27.8%) was lower compared to those without FJV (71.2%) (P =.0002). Patients with FJV were 76% less likely to have a successful fusion at 12-months. Conclusion: Pedicle screw-associated violation of the adjacent unfused facet joint during single-level lumbar fusion is associated with less improvement in back pain, back pain-associated disability, and a lower fusion rate at 1-year after surgery.