Radiological and Functional Outcomes of Single vs. Multiple Level TLIF Using Local Corticocancellous Bone Grafts: A Retrospective-Prospective Study

Background: Transforaminal lumbar interbody fusion (TLIF) is a widely accepted surgical procedure for treating lumbar spinal instability and degenerative disorders. While interbody fusion can be achieved using autografts, the utilization of local corticocancellous bone grafts presents a promising alternative. However, the comparative effectiveness of single- versus multi-level TLIF using this graft type remains underexplored. Objective: To assess and compare the radiological and functional outcomes of single- and multi-level TLIF using local corticocancellous laminectomy bone grafts. Methods: A retro-prospective observational study was conducted on 100 patients who underwent TLIF over a 12-month period at a tertiary care center. Patients were categorized into single-level (n=60) and multiple-level (n=40) TLIF groups. Radiological outcomes were measured using anterior disc height (ADH), posterior disc height (PDH), segmental kyphosis (SK), and foraminal height (FH) at preoperative, immediate postoperative, 3month, and 1-year intervals. Functional outcomes were assessed using Visual Analog Scale (VAS) and Oswestry Disability Index (ODI). Data were analyzed using descriptive statistics and inferential comparisons (p<0.05 considered significant). Results: At 1 year, both groups showed significant improvements in ODI (Single-level: 12.23 ± 2.01; Multilevel: 14.98 ± 2.34; p=0.018) and VAS (Single-level: 2.31 ± 0.94; Multi-level: 2.92 ± 0.98; p=0.041). Radiological improvements were greater in the single-level group with higher gains in ADH (3.72 ± 0.47 vs. 3.08 ± 0.52 mm; p=0.006) and PDH (3.26 ± 0.38 vs. 2.93 ± 0.46 mm; p=0.012). SK and FH improvements were observed in both groups without significant differences (p>0.05). Conclusion: Both single- and multiple-level TLIF using local corticocancellous grafts result in favorable clinical and radiological outcomes. However, single-level TLIF demonstrated superior improvements in disc height and disability scores, supporting its efficiency for isolated lumbar pathologies.