Impact of Single-Level Minimally Invasive Versus Open L4-L5 and L5-S1 Transforaminal Lumbar Interbody Fusion on Postoperative Distal and Lumbar Lordosis.

Study Design: Retrospective cohort study.

Objective: To compare distal lordosis (DL) and lumbar lordosis (LL) generated by single-level minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) and open TLIF at L4-L5 and L5-S1.

Summary Of Background Data: Restoring or maintaining L4-S1 DL and LL is an important component of TLIF surgery. However, the current literature is conflicting regarding the effect of surgical approach on these postoperative sagittal parameters.

Methods: Preoperative DL and LL were compared to postoperative values among adult patients undergoing single-level MI- and open TLIF surgeries. Subgroup analyses were performed with patients stratified based on pre-operative DL (low<25°, normal ≥ 25°), pelvic incidence (PI) (low<45°, moderate 45-60°, high > 60°), and PI-LL (high ≥ 10°, normal <10°). Regression analyses were conducted determining factors associated with postoperative DL and LL.

Results: Of the 285 patients included in the study, 211 underwent MI-TLIF (74.0%) and 74 (26.0%) underwent open TLIF. Patients with a high preoperative PI obtained a significant increase in LL at 6-month follow-up with an open TLIF (Δ4.2°, P=0.009) but not with an MI-TLIF (Δ-0.8°, P=0.151). Patients with a preoperative DL ≥ 25° experienced a decrease in DL at 6-month follow-up with both an open TLIF (Δ-2.0°, P=0.013) and MI-TLIF (Δ-1.4°, P=0.011). Patients with a preoperative DL ≥ 25° also experienced a decrease in LL at 6-month follow-up with an MI-TLIF (Δ-1.0°, P=0.002) but not with an open TLIF (Δ-0.3°, P=0.552). Patients with a preoperative DL<25° obtained an increase in both DL and LL with both MI-TLIF and open TLIF.

Conclusion: Both MI-TLIF and open TLIF are effective for improving DL and LL among patients with a low preoperative DL (<25°). However, patients with a high preoperative PI (>60°) may benefit from an open approach for a greater restoration and maintenance of LL.

Level Of Evidence: 3.