Psoas Atrophy Following Lateral Lumbar Interbody Fusion: A Retrospective Case Series.
- 1Department of Orthopaedic Surgery, Keck School of Medicine at the University of Southern California, Los Angeles, CA, USA.
Abstract
Background
The direct muscular trauma caused by the trans-psoas approach of a lateral lumbar interbody fusion (LLIF) is a potential reason for its high rates of postoperative psoas weakness.Purpose
We sought to compare preoperative and postoperative psoas muscle parameters to evaluate iatrogenic psoas atrophy following LLIF.Methods
We conducted a retrospective case series including patients who underwent primary LLIF at a single tertiary academic center between 2012 and 2024. Exclusion criteria included history of spinal deformity, spine surgery, neuromuscular disorders, or LLIF indicated for infection or malignancy. Participants had both preoperative and postoperative magnetic resonance imaging (MRI) scans; the latter were obtained at least 3 months postoperatively. Psoas muscle atrophy was assessed using MRI measurements of cross-sectional area (CSA), anteroposterior (AP) and mediolateral diameters, and Goutallier classification for fatty infiltration. Paired and Welch's t-tests compared postoperative to preoperative and contralateral values. Subgroup analysis compared patients with and without postoperative hip flexor weakness.Results
Forty patients met inclusion criteria (mean follow-up: 25 months). The ipsilateral psoas demonstrated significant reduction in CSA (-117 vs -22.7 mm²) and AP diameter (-2.43 vs 0.34 mm) compared with the contralateral side. Six patients (15%) had persistent hip flexor weakness. On multivariate analysis, male sex and body mass index (BMI) were risk factors for psoas atrophy. Diabetes and length of stay predicted postoperative hip flexor weakness.Conclusions
This retrospective study identified evidence of long-term ipsilateral psoas atrophy following LLIF, potentially contributing to postoperative hip flexor weakness. Male sex, BMI, diabetes, and length of hospital stay were identified as predictors of psoas atrophy or weakness, highlighting the importance of postoperative rehabilitation focusing on psoas preservation. Future studies are warranted to further evaluate potential risk factors for postoperative hip flexor weakness following LLIF.Level of evidence
Level IV: retrospective case series.
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BibTeX
@article{rusu2026psoas,
title = {{Psoas Atrophy Following Lateral Lumbar Interbody Fusion: A Retrospective Case Series.}},
author = {Daniel Rusu and Kevin Sun and Brandon Yoshida and Aidan R Lindgren and Henry Avetisian and William J Karakash and Marc A Abdou and Jeffrey C Wang and Raymond J Hah and Ram K Alluri},
journal = {HSS journal : the musculoskeletal journal of Hospital for Special Surgery},
year = {2026},
month = oct,
doi = {10.1177/15563316261497327},
url = {https://europepmc.org/article/MED/42968992},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Psoas Atrophy Following Lateral Lumbar Interbody Fusion: A Retrospective Case Series.
AU - Daniel Rusu
AU - Kevin Sun
AU - Brandon Yoshida
AU - Aidan R Lindgren
AU - Henry Avetisian
AU - William J Karakash
AU - Marc A Abdou
AU - Jeffrey C Wang
AU - Raymond J Hah
AU - Ram K Alluri
PY - 2026
DA - 2026/10/30
JO - HSS journal : the musculoskeletal journal of Hospital for Special Surgery
DO - 10.1177/15563316261497327
UR - https://europepmc.org/article/MED/42968992
AB - Background The direct muscular trauma caused by the trans-psoas approach of a lateral lumbar interbody fusion (LLIF) is a potential reason for its high rates of postoperative psoas weakness.Purpose We sought to compare preoperative and postoperative psoas muscle parameters to evaluate iatrogenic psoas atrophy following LLIF.Methods We conducted a retrospective case series including patients who underwent primary LLIF at a single tertiary academic center between 2012 and 2024. Exclusion criteria included history of spinal deformity, spine surgery, neuromuscular disorders, or LLIF indicated for infection or malignancy. Participants had both preoperative and postoperative magnetic resonance imaging (MRI) scans; the latter were obtained at least 3 months postoperatively. Psoas muscle atrophy was assessed using MRI measurements of cross-sectional area (CSA), anteroposterior (AP) and mediolateral diameters, and Goutallier classification for fatty infiltration. Paired and Welch's t-tests compared postoperative to preoperative and contralateral values. Subgroup analysis compared patients with and without postoperative hip flexor weakness.Results Forty patients met inclusion criteria (mean follow-up: 25 months). The ipsilateral psoas demonstrated significant reduction in CSA (-117 vs -22.7 mm²) and AP diameter (-2.43 vs 0.34 mm) compared with the contralateral side. Six patients (15%) had persistent hip flexor weakness. On multivariate analysis, male sex and body mass index (BMI) were risk factors for psoas atrophy. Diabetes and length of stay predicted postoperative hip flexor weakness.Conclusions This retrospective study identified evidence of long-term ipsilateral psoas atrophy following LLIF, potentially contributing to postoperative hip flexor weakness. Male sex, BMI, diabetes, and length of hospital stay were identified as predictors of psoas atrophy or weakness, highlighting the importance of postoperative rehabilitation focusing on psoas preservation. Future studies are warranted to further evaluate potential risk factors for postoperative hip flexor weakness following LLIF.Level of evidence Level IV: retrospective case series.
SN - 1556-3316
SN - 1556-3324
ER -