Minimally invasive vs. open transforaminal lumbar interbody fusion for grade I
lumbar spondylolisthesis
April 27, 2025
Cohort Study
Coh:NA-MD.04
Abstract
OBJECTIVE: This study compares the long-term outcomes of minimally invasive TLIF (MI-TLIF) to traditional open TLIF for grade I degenerative lumbar spondylolisthesis at 60 months postoperatively.
CONCLUSIONS: For symptomatic, single-level grade I degenerative lumbar spondylolisthesis, MI-TLIF was associated with decreased blood loss perioperatively, but there was no difference in 60-month outcomes for disability, back pain, leg pain, quality of life, or satisfaction between MI and open TLIF. There was no difference in cumulative reoperation rates between the two procedures. These results suggest that in appropriately selected patients, either procedure may be employed depending on patient and surgeon preferences.
Background
Degenerative lumbar spondylolisthesis is a common condition affecting an estimated 13.6% of the United States population. For symptomatic patients in whom nonoperative treatment fails, surgery is efficacious. Surgical techniques have evolved from open decompression to approaches including spinal arthrodesis via posterolateral approaches or interbody devices, and more recently to minimally invasive approaches.
MI-TLIF was first described by Foley and Lefkowitz in 2002. Unlike traditional open TLIF, which involves a midline posterior approach with paraspinal musculature dissection, MI-TLIF uses a paramedian Wiltse plane approach that avoids extensive musculature dissection and limits incision size.
Methods
Study Design
Retrospective analysis of prospectively collected data using an augmented data set from the Quality Outcomes Database (QOD) lumbar module. The study queried for patients who had undergone single-segment TLIF surgery for grade I lumbar spondylolisthesis via either an MI or an open approach from July 2014 through June 2016.
Patient Population
- Total patients: 297
- MI-TLIF: 72 patients (24.2%)
- Open TLIF: 225 patients (75.8%)
- 60-month follow-up rates: 86.1% for MI-TLIF vs 75.6% for open TLIF (p = 0.06)
Outcome Measures
Primary outcome: Oswestry Disability Index (ODI)
Secondary outcomes:
- Numeric rating scale (NRS) for back pain (NRS-BP)
- NRS for leg pain (NRS-LP)
- EQ-5D quality of life measure
- North American Spine Society (NASS) satisfaction
- Cumulative reoperation rate
Statistical Analysis
Multivariable models were constructed to assess the impact of MI-TLIF on PROs, adjusting for variables reaching p < 0.20 on univariable analyses and respective baseline PRO values.
Results
Baseline Characteristics
| Characteristic | Open TLIF (n=225) | MI-TLIF (n=72) | p Value |
|---|---|---|---|
| Age (years) | 59.5 ± 11.7 | 62.1 ± 10.6 | 0.10 |
| Female | 143 (63.6%) | 40 (55.6%) | 0.22 |
| BMI | 31.3 ± 7.0 | 29.5 ± 5.1 | 0.0497 |
| Motor deficit at presentation | 53 (23.6%) | 4 (5.6%) | <0.001 |
| Baseline ODI | 48.0 ± 16.6 | 46.2 ± 16.3 | 0.41 |
| Baseline NRS-BP | 7.0 ± 2.3 | 6.9 ± 2.6 | 0.70 |
| Baseline NRS-LP | 6.6 ± 2.8 | 6.3 ± 2.8 | 0.41 |
Perioperative Parameters
| Parameter | Open TLIF | MI-TLIF | p Value |
|---|---|---|---|
| Estimated blood loss (ml) | 299.6 ± 242.2 | 108.8 ± 85.6 | <0.001 |
| Operative time (minutes) | 189.6 ± 66.5 | 228.2 ± 111.5 | <0.001 |
| Length of hospitalization (days) | 3.3 ± 1.6 | 2.9 ± 1.8 | 0.08 |
| Discharge to home/home health | 91.1% | 93.1% | 0.60 |
| 30-day complications | 7.6% | 6.9% | 0.86 |
60-Month Outcomes
| Outcome | Open TLIF | MI-TLIF | Unadjusted p Value | Adjusted p Value |
|---|---|---|---|---|
| ODI score | 24.8 ± 19.0 | 18.9 ± 18.4 | 0.04 | 0.31 |
| Change in ODI | -21.8 ± 19.6 | -26.1 ± 21.5 | 0.16 | 0.43 |
| ODI MCID reached | 65.7% | 74.2% | 0.22 | 0.45 |
| NRS-BP score | 3.7 ± 3.1 | 2.8 ± 2.9 | 0.048 | 0.23 |
| NRS-LP score | 2.8 ± 3.1 | 1.8 ± 2.8 | 0.03 | 0.17 |
| Reoperation rate | 11.6% | 5.6% | 0.14 | – |
Key Outcome Findings
- Both MI-TLIF and open TLIF groups showed significant improvements from baseline in ODI, NRS-BP, NRS-LP, and EQ-5D (p < 0.001 for all comparisons)
- Before adjustment, MI-TLIF showed better ODI, NRS-BP, and NRS-LP scores, but these differences disappeared after adjustment for baseline variables
- NASS satisfaction scores: Despite a statistically significant difference in unadjusted analysis (p = 0.04), similar proportions of patients reported the highest satisfaction score (MI-TLIF 69.8% vs open TLIF 72.3%)
- Reasons for reoperation: Adjacent-segment disease was the most common reason in both groups
Discussion
This study represents the largest single-study cohort comparing MI-TLIF and open TLIF with a minimum 60-month follow-up for grade I degenerative lumbar spondylolisthesis. The investigation found that:
- MI-TLIF was associated with less blood loss but slightly longer operative times compared to open TLIF
- After accounting for baseline differences, long-term outcomes for disability, pain, quality of life, and patient satisfaction were similar between procedures
- Cumulative reoperation rates at 60 months were not significantly different between the two procedures
- Both approaches demonstrated significant improvements from baseline for all measured outcomes
Clinical Implications
These findings suggest that both MI-TLIF and open TLIF provide durable long-term outcomes for patients with grade I degenerative lumbar spondylolisthesis. The choice between procedures can be based on surgeon expertise, patient characteristics, and specific clinical scenarios where one approach might offer advantages (e.g., when minimal blood loss is critical).
The study extends previous literature showing equivalent short-term results by demonstrating that this equivalence persists at 5-year follow-up. This contradicts some earlier findings which suggested superior outcomes for MI-TLIF at 24 months that weren’t sustained at longer follow-up periods.
Study Limitations
- Retrospective analysis of prospective data with potential selection bias
- Inability to control for surgeon and patient selection between open and MI-TLIF techniques
- Potential variations in surgical technique despite standardized definitions
- Some baseline differences between cohorts (BMI, motor deficits, workers’ compensation)
- Limited radiographic parameters assessed (though key outcomes like fusion and reoperation were captured)
- Some patients lost to follow-up (though 60-month follow-up rates were high: 75.6-86.1%)
Conclusion
For symptomatic, single-level grade I degenerative lumbar spondylolisthesis, MI-TLIF was associated with decreased blood loss perioperatively, but there was no difference in 60-month outcomes for disability, back pain, leg pain, quality of life, or satisfaction between MI and open TLIF.
There was no difference in cumulative reoperation rates between the two procedures. These results suggest that in appropriately selected patients, either procedure may be employed depending on patient and surgeon preferences.
Procedure Visualization
Figure 1: Depiction of an MI-TLIF. © Andrew K. Chan, published with permission.