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Updated: Jan 18, 2026
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Surgical Approach and Complications of Stand-alone Lateral Trans-Psoas Interbody Fusion
Published on: February 14, 2025
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Lateral Lumbar Interbody Fusion (LLIF): Is Trans-Psoas Surgery Associated with Muscle Size Changes and Clinical
Luke Jouppi1, Clifford Pierre1, Neel Patel2
1Swedish Neuroscience Institute, Swedish Medical Center, Seattle, Washington, USA; Seattle Science Foundation, Seattle, Washington, USA.
World Neurosurgery
|September 7, 2025
Summary
Lateral lumbar interbody fusion (LLIF) causes minor long-term psoas size reduction and small bilateral strength losses. This minimally invasive spine surgery approach does not lead to side-specific sensory deficits.
Area of Science:
- Spine surgery
- Orthopedics
- Neurosurgery
Background:
- Lateral lumbar interbody fusion (LLIF) is a minimally invasive spinal fusion technique.
- Concerns exist regarding potential postoperative hip flexor weakness and nerve issues on the surgical side.
Purpose of the Study:
- To investigate long-term changes in psoas morphology after LLIF.
- To assess hip flexor strength and lower extremity sensation following LLIF.
Main Methods:
- Retrospective review of 108 LLIF patients with pre- and post-operative MRI.
- Psoas cross-sectional area measurements.
- Analysis of motor and sensory examinations and patient-reported symptoms.
Main Results:
- A statistically significant mean decrease of 6.3% in surgical-side psoas size was observed (inconsequential effect size).
- No significant change in psoas size occurred on the non-surgical side.
- Hip flexor strength decreased by ≥ 1 grade in 14.5% of patients on the surgical side versus 9.1% on the non-surgical side, with no significant difference.
Conclusions:
- LLIF is associated with minor long-term decreases in surgical-side psoas size.
- Small, non-significant bilateral hip flexor strength losses were noted.
- No side-specific sensory deficits were identified after LLIF.
