EDITED BY Carlos A Bagley, University of Texas Southwestern Medical Center, United States REVIEWED BY Haiyang Wu, Tianjin Medical University, China Roberto Altieri, University of Catania, Italy *CORRESPONDENCE Salvatore Petrone svt.petrone@gmail.com SPECIALTY SECTION This article was submitted to Neurosurgery, a section of the journal Frontiers in Surgery RECEIVED 04 February 2023 ACCEPTED 20 March 2023 PUBLISHED 03 April 2023 CITATION Petrone S, Ajello M, Marengo N, Bozzaro M, Pesaresi A, Allevi M, Fiumefreddo A, Denegri F, Cogoni M, Garnero A, Tartara F, Di Perna G, Armocida D, Pesce A, Frati A, Zenga F, Garbossa D and Cofano F (2023) Clinical outcomes, MRI evaluation and predictive factors of indirect decompression with lateral transpsoas approach for lumbar interbody fusion: a multicenter experience. Front. Surg. 10:1158836. doi: 10.3389/fsurg.2023.1158836 COPYRIGHT © 2023 Petrone, Ajello, Marengo, Bozzaro, Pesaresi, Allevi, Fiumefreddo, Denegri, Cogoni, Garnero, Tartara, Di Perna, Armocida, Pesce, Frati, Zenga, Garbossa and Cofano. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Clinical outcomes, MRI evaluation and predictive factors of indirect decompression with lateral transpsoas approach for lumbar interbody fusion: a multicenter experience Salvatore Petrone 1,2 * , Marco Ajello 3 , Nicola Marengo 3 , Marco Bozzaro 1 , Alessandro Pesaresi 2 , Mario Allevi 2 , Alessandro Fiumefreddo 3 , Federica Denegri 4 , Maurizio Cogoni 4 , Andrea Garnero 4 , Fulvio Tartara 1 , Giuseppe Di Perna 2,5 , Daniele Armocida 6 , Alessandro Pesce 7 , Alessandro Frati 6 , Francesco Zenga 8 , Diego Garbossa 2,3 and Fabio Cofano 1,2 1 Spine Surgery Unit, Humanitas Gradenigo Turin, Turin, Italy, 2 Neurosurgery Unit, University of Turin Department of Neurosciences Rita Levi Montalcini, Turin, Italy, 3 Neurosurgery Unit, AOU Città della Salute e della Scienza, Turin, Italy, 4 Neuroradiology Unit, AOU Città della Salute e della Scienza, Turin, Italy, 5 Spine Surgery Unit, Casa di Cura Città di Bra, Bra, Italy, 6 Neurosurgery Unit, Department of Human Neuroscience, University Sapienza of Rome, Rome, Italy, 7 Neurosurgery Unit, Ospedale Santa Maria Goretti, Latina, Italy, 8 Skull Base and Pituitary Surgery Unit, AOU Città Della Salute e Della Scienza, Turin, Italy Introduction: Evaluating the effects of indirect decompression obtained through lateral lumbar interbody fusion (LLIF) by clinical improvements and radiological parameters on MRI scans. Identifying predictors of better decompression and clinical outcome. Materials and methods: From 2016 to 2019, patients who underwent single- or double-level indirect decompression LLIF were consecutively reviewed. Radiological signs of indirect decompression were evaluated in preoperative and follow-up MRI studies and were subsequently correlated to clinical data, expressed as axial/radicular pain (VAS back/leg), index of disability (Oswestry Disability Index) and clinical severity of lumbar stenosis (Swiss Spinal Stenosis Questionnaire). Results: 72 patients were enrolled. The mean follow-up was 24 months. Differences in vertebral canal area ( p < 0.001), height of the foramina ( p < 0.001), thickness of the yellow ligament ( p = 0.001) and anterior height of the interbody space ( p = 0.02) were observed. Older age ( p = 0.042), presence of spondylolisthesis ( p = 0.042), presence of intra-articular facet effusion ( p = 0.003) and posterior height of the implanted cage ( p = 0.020) positively affected the increase of the canal area. Change in root canal area ( p < 0.001), height of the implanted cage ( p = 0.020) and younger age ( p = 0.035) were predictive factors of root pain relief, while increased vertebral canal area ( p = 0.020) and height of the interbody fusion cage ( p = 0.023) positively affected the severity of clinical stenosis. Conclusions: LLIF indirect decompression showed both clinical and radiological improvements. Presence and degree of spondylolisthesis, presence of intra- articular facet effusion, age of the patient and height of the cage were predictive factors of major clinical improvements. KEYWORDS indirect decompression, LLIF, XLIF, spondylolisthesis, predictive factors TYPE Original Research PUBLISHED 03 April 2023 | DOI 10.3389/fsurg.2023.1158836 Frontiers in Surgery 01 frontiersin.org