Minimally Invasive Transforaminal Versus Lateral Lumbar Interbody Fusion for Degenerative Spinal Pathology: Clinical Outcome Comparison in Patients With Predominant Back Pain.

Study design: Retrospective review.

Objective: To compare perioperative and postoperative clinical outcomes between minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) and lateral lumbar interbody fusion (LLIF) in patients presenting with predominant back pain.

Background: Two popular techniques utilized for lumbar arthrodesis are MIS-TLIF and LLIF. Both techniques have reported high fusion rates and suitable postoperative clinical outcomes. Scarce literature exists, however, comparing these 2 common fusion techniques in a subset population of patients presenting with predominant back pain preoperatively.

Methods: A retrospective review of lumbar procedures performed between November 2005 and December 2021 was conducted using a prospectively maintained single-surgeon database. Inclusion criteria were set as primary, elective, single, or multilevel MIS-TLIF or LLIF procedures for degenerative spinal pathology in patients with predominant preoperative back pain [visual analog scale (VAS) back pain preoperative score > VAS leg preoperative score]. Patients undergoing a revision procedure, single-level procedure at L5-S1, or surgery indicated for infectious, malignant, or traumatic etiologies were excluded. In addition, patients with VAS leg preoperative scores ≥ to VAS back preoperative scores were excluded. Patient demographics, perioperative characteristics, postoperative complications, and patient-reported outcome measures (PROMs) were collected. PROMs included VAS for back and leg pain, Oswestry Disability Index (ODI), and Short Form-12 (SF-12) Item Survey Mental (MCS) and Physical (PCS) Composite Scores with all values collected at the preoperative, 6-week, 12-week, 6-month, 1-year, and 2-year follow-up time point. Patients were grouped into 2 cohorts, depending on whether a patient underwent a MIS-TLIF or LLIF. Demographic and perioperative characteristics were compared between groups using χ 2 and Student t test for categorical and continuous variables, respectively. Mean PROM scores were compared between cohorts at each time point utilizing an unpaired Student t test. Postoperative improvement from preoperative baseline within each cohort was assessed with paired samples t test. Achievement of minimum clinical important difference (MCID) was determined by comparing ΔPROM scores to previously established threshold values. MCID achievement rates were compared between groups with χ 2 analysis. Statistical significance was noted as a P value <0.05.

Results: Eligible study cohort included 153 patients, split into 106 patients in the MIS-TLIF cohort and 47 patients in the LLIF cohort. The mean age was 55.9 years, the majority (57.5%) of patients were males, the mean body mass index was 30.8 kg/m 2 , and the majority of the included cohort were nondiabetic and nonhypertensive. No significant demographic differences were noted between cohorts. The MIS-TLIF cohort had a significantly greater proportion of patients with preoperative spinal pathology of recurrent herniated nucleus pulposus, whereas a significantly greater proportion of patients in the LLIF cohort demonstrated isthmic spondylolisthesis ( P < 0.046, all). No significant differences were noted between cohorts for operative duration, estimated blood loss, 1-year rate of arthrodesis, postoperative length of stay, postoperative VAS pain scores on postoperative day 0 or 1, and postoperative narcotic consumption on postoperative day 0 or 1. Patients in the LLIF cohort showed greater rates of postoperative ileus (4.3% vs 0.0%). No other significant differences were noted between cohorts for postoperative complications. Between cohorts, preoperative PROM scores did not significantly differ. The following significant postoperative mean PROM scores were demonstrated: VAS back at 12 weeks and ODI at 12 weeks with both mean scores favoring the LLIF cohort. The MIS-TLIF cohort reported significant improvement from preoperative baseline to the 2-year time point for all PROMs collected at all individual postoperative time points except SF-12 MCS at 6 weeks ( P < 0.0, all). LLIF cohort reported significant improvement from preoperative baseline to the 1-year time point for all PROMs collected at all individual postoperative time points except for ODI at 6 weeks, 1 year, and 2 years, SF-12 MCS at 6 weeks and 2 years, and SF-12 PCS at 2 years( P < 0.042, all). The majority of patients in both cohorts achieved overall MCID for VAS back, VAS leg, ODI, and SF-12 PCS. A significantly greater proportion of patients in the LLIF cohort achieved MCID for SF-12 PCS at 12 weeks (94.4% vs 61.1%; P < 0.008).

Conclusion: Patients with predominant back pain undergoing MIS-TLIF or LLIF for degenerative spinal pathology demonstrated similar 2-year mean clinical outcomes for physical function, disability, leg pain, and back pain. At the 12-week time point, mean outcome scores for back pain and disability favored the lateral approach with concurrent higher rates of MCID achievement for physical function at that time point.