MIS-TLIF Achieves Comparable Outcomes in Challenging Spondylolisthesis Cases: Radiographic Difficulty Assessed with a Novel Grading System.

Abstract

Study design: Retrospective analysis.

Objective: To compare clinical outcomes of minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) among patients with different radiographical difficult spondylolisthesis.

Summary of background context: High-grade vertebral slip, collapsed disc, and less mobile segment can complicate segmental parameter restoration in MIS-TLIF. Few studies have examined if MIS-TLIF can achieve comparable outcomes in these challenging cases.

Materials and methods: This study included patients who underwent single-level MIS-TLIF for degenerative spondylolisthesis. Radiographical difficulty was defined using a "difficulty point" system: disc height (<5 mm=1point), angular flexibility at the operated level by preoperative flexion-extension standing X-ray (<5degrees=1point), and slippage rate (>25%=1 point). Patients were categorized into "simple" (0 point), "moderate" (1 point), and "difficult" (2-3 points) cohorts. Outcomes included radiographic parameters (postoperative disc height, segmental lordosis restoration, and slippage reduction), complications, patient-reported outcomes such as Oswestry Disability Index (ODI) from 2 weeks to 1 year postoperatively.

Results: A total of 208 patients were included, with 52 in the difficult, 89 in the moderate, and 67 in the simple. The difficult cohort showed significantly greater restoration of disc height (161.0% vs. 26.5% vs. 9.3%, P<0.001), resulting in similar postoperative disc height (8.3 mm vs. 9.0 mm vs. 0.1 mm, P=0.10) and segmental lordosis at the operated level (14.5 vs. 13.0 vs. 12.5 degrees, P=0.17). Postoperative outcomes indicated a greater improvement trend in ODI in the difficult group compared to the moderate group (β= 7.3, 9=0.011), with similar minimal clinically important difference achievement rate in ODI at 1-year postoperatively (Difficult, 69.2% vs. Moderate, 62.8% vs. Simple, 54.3%, P=0.46).

Conclusion: MIS-TLIF is a feasible treatment option in patients with technically challenging radiographic parameters, achieving comparable postoperative radiographical and clinical outcomes.

Level of evidence: 3.