Radiological and Clinical Outcomes comparing 2-level MIS Lateral and MIS Transforaminal Lumbar Interbody Fusion in Degenerative Lumbar Spinal Stenosis

Study design: Retrospective Cohort Study Objectives: To compare early postoperative radiological and clinical outcomes between 2-level minimally invasive (MIS) trans-psoas lateral lumbar interbody fusion (LLIF) and MIS transforaminal lumbar interbody fusion (TLIF) for degenerative lumbar spinal stenosis. Methods: Fifty three consecutive patients undergoing 2-level lumbar interbody fusion from L3-L5 for degenerative lumbar spinal stenosis were enrolled. Twenty four patients underwent LLIF and 29 underwent TLIF. Results: Operative time and length of stay were similar between LLIF and TLIF (272.8 +/- 82.4 vs 256.1 +/- 59.4 minutes; 5.5 +/- 2.8 vs 4.7 +/- 3.3 days, P > .05), whereas blood loss was lower for LLIF (229.0 +/- 125.6 vs 302.4 +/- 97.1mls, P = .026). Neurological deficits were more common in LLIF (9 vs 3, P = .025), whereas persistent deficits were rare for both (1 vs 1, P = 1). For both groups, all patient reported outcomes visual analogue scale (VAS back pain, VAS leg pain, ODI, SF-36 physical) improved from preoperative to 2-years postoperative (P < .05), with both groups showing no significant differences in extent of improvement for any outcome. Lateral lumbar interbody fusion demonstrated superior restoration of disc height (L3-L4: 4.1 +/- 2.4 vs 1.2 +/- 1.9 mm, P < .001; L4-L5: 4.6 +/- 2.4 vs .8 +/- 2.8 mm, P < .001), foraminal height (FH) (L3-L4: 3.5 +/- 3.6 vs 1.0 +/- 3.6 mm, P = .014; L4-L5: 3.0 +/- 3.5 vs -.1 +/- 4.4 mm, P = .0080), segmental lordosis (4.1 +/- 6.4 vs -2.1 +/- 8.1 degrees, P = .005), lumbar lordosis (LL) (4.1 +/- 7.0 vs -2.3 +/- 12.6 degrees, P = .026) and pelvic incidence-lumbar lordosis (PI-LL) mismatch (-4.1 +/- 7.0 vs 2.3 +/- 12.6 degrees, P = .019) at 2-years follow-up. Conclusion: The superior radiological outcomes demonstrated by 2-level trans-psoas LLIF did not translate into difference in clinical outcomes compared to 2-level TLIF at the 2-years follow-up, suggesting both approaches are reasonable for 2-level lumbar interbody fusion in degenerative lumbar spinal stenosis.