Fusion Outcomes after Unilateral versus Bilateral Facetectomy in L4–5 Transforaminal Lumbar Interbody Fusion: A Retrospective Cohort Study

Objective: The optimal extent of facetectomy during single-level transforaminal lumbar interbody fusion (TLIF) remains unclear.This study compared radiographic fusion outcomes between total laminectomy with unilateral facetectomy and total laminectomy with bilateral facetectomy in patients undergoing single-level L4-5 TLIF.Methods: This retrospective cohort study included patients who underwent single-level L4-5 TLIF between March 2020 and March 2025.Of 87 initially screened patients, 51 met the inclusion criteria and were included in the final analysis.Patients were grouped according to the extent of facetectomy: unilateral facetectomy (n = 23) or bilateral facetectomy (n = 28).All patients underwent interbody cage insertion and bilateral pedicle screw fixation at L4 and L5.Radiographic fusion was assessed at the final follow-up using computed tomography and/or dynamic radiographs.Bridwell grades I and II were classified as fusion, whereas grades III and IV were classified as non-fusion.Baseline characteristics and fusion rates were compared between the groups.Results: The mean radiographic follow-up period was 18.4 ± 14.2 months.Baseline characteristics, including age, body mass index, sex, bone mineral density category, diagnosis, smoking status, diabetes mellitus, and hypertension, did not differ significantly between the groups.Fusion was achieved in 21 of 23 patients in the unilateral facetectomy group and 24 of 28 patients in the bilateral facetectomy group.The fusion rates were 91.3% and 85.7%, respectively, with no statistically significant between-group difference (p = 0.678).Conclusion: In this retrospective cohort of patients undergoing single-level L4-5 TLIF with total laminectomy, radiographic fusion rates did not differ significantly between unilateral and bilateral facetectomy.However, the small sample size and limited number of non-fusion events preclude conclusions regarding equivalence or noninferiority.Larger studies are needed to clarify whether facetectomy extent affects fusion outcomes after L4-5 TLIF.