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Updated: Aug 7, 2025
Surgical Approach and Complications of Stand-alone Lateral Trans-Psoas Interbody Fusion
Published on: February 14, 2025
What is the fate of the adjacent segmental angles 6 months after single-level L3-4 or L4-5 lateral lumbar interbody
Luke Verst1, Caroline E Drolet2, Jesse Shen2
1Department of Neurosurgery, Center for Neurosciences and Spine, Virginia Mason Franciscan Health, 1100 Ninth Ave, Seattle, WA 98101, USA; School of Medicine, University of Washington, 1959 NE Pacific St, Seattle, WA 98195 USA.
Background Context:
Lateral lumbar interbody fusion (LLIF) is an effective technique for fusion and sagittal alignment correction/maintenance. Studies have investigated the impact on the segmental angle and lumbar lordosis (and pelvic incidence-lumbar lordosis mismatch), however not much is documented regarding the immediate compensation of the adjacent angles.
Purpose:
To evaluate acute adjacent and segmental angle as well as lumbar lordosis changes in patients undergoing a L3-4 or L4-5 LLIF for degenerative pathology.
Study Design/Setting:
Retrospective cohort study.
Patient Sample:
Patients included in this study were analyzed pre- and post-LLIF performed by one of three fellowship-trained spine surgeons, 6 months following surgery.
Outcome Measures:
Patient demographics (including body mass index, diabetes diagnosis, age, and sex) as well as VAS and ODI scores were measured. Lateral lumbar radiograph parameters: lumbar lordosis (LL), segmental lordosis (SL), infra and supra-adjacent segmental angle, and pelvic incidence (PI).
Methods:
Multiple regressions were applied for the main hypothesis tests. We examined any interactive effects at each operative level and used the 95% confidence intervals to determine significance: a confidence interval excluding zero indicates a significant effect.
Results:
We identified 84 patients who underwent a single level LLIF (61 at L4-5, 23 at L3-4). For both the overall sample and at each operative level, the operative segmental angle was significantly more lordotic postop compared to preop (all ps≤.01). Adjacent segmental angles were significantly less lordotic postop compared to pre-op overall (p=.001). For the overall sample, greater lordotic change at the operative segment led to more compensatory reduction of lordosis at the supra-adjacent segment. At L4-5, more lordotic change at the operative segment led to more compensatory lordosis reduction at the infra-adjacent segment.
Conclusion:
The present study demonstrated that LLIF resulted in significant increase in operative level lordosis and a compensatory decrease in supra- and infra-adjacent level lordosis, and subsequently no significant impact on spinopelvic mismatch.
