26dkou220 10.3205/26dkou220 urn:nbn:de:0183-26dkou2203 Meeting Abstract Gerstmeyer Gerstmeyer Julius J

Swedish Neuroscience Institute, Seattle, USA Seattle Science Foundation, Seattle, USA Klinik für Orthopädie und Unfallchirurgie, St. Josef Hospital, Bochum, Deutschland

author Jouppi Jouppi Luke L

Swedish Neuroscience Institute, Seattle, USA Seattle Science Foundation, Seattle, USA

author Pierre Pierre Clifford C

Swedish Neuroscience Institute, Seattle, USA Seattle Science Foundation, Seattle, USA

author Patel Patel Neel N

Swedish Neuroscience Institute, Seattle, USA Seattle Science Foundation, Seattle, USA Center for Minimally Invasive Neurosurgery, Houston, USA

author Minissale Minissale Nicholas N

Swedish Neuroscience Institute, Seattle, USA Seattle Science Foundation, Seattle, USA

author Gold Gold Colin C

Swedish Neuroscience Institute, Seattle, USA

author Hogsett Hogsett Cameron C

Swedish Neuroscience Institute, Seattle, USA Seattle Science Foundation, Seattle, USA

author Norvell Norvell Daniel C. DC

Spectrum Research Consulting, Tacoma, USA

author Abdul-Jabbar Abdul-Jabbar Amir A

Swedish Neuroscience Institute, Seattle, USA

author Oskouian Oskouian Rod R

Swedish Neuroscience Institute, Seattle, USA Seattle Science Foundation, Seattle, USA

author Chapman Chapman Jens J

Swedish Neuroscience Institute, Seattle, USA Seattle Science Foundation, Seattle, USA

author German Medical Science GMS Publishing House

Düsseldorf

610 20261020 engl This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). M0659 220 Deutsche Gesellschaft für Orthopädie und Unfallchirurgie Deutsche Gesellschaft für Orthopädie und Orthopädische Chirurgie Deutsche Gesellschaft für Unfallchirurgie Berufsverband für Orthopädie und Unfallchirurgie Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2026) Abstracts | Moderne operative Wirbelsäulenchirurgie Berlin 20261020 20261023 DKOU26_Abs_2379 TextObjectives and questions: Lateral lumbar interbody fusion (LLIF) is based on a less-invasive access corridor through the retroperitoneum and psoas muscle, though concerns persist over postoperative weakness and neuropathy on the surgical side. This study investigates if the trans-psoas LLIF approach is associated with long-term changes in psoas morphology, hip flexor weakness, and lower extremity dysesthesia.Material and methods: The authors retrospectively reviewed all LLIF cases at a single institution from January 2016 to June 2024. Inclusion required the availability of preoperative and postoperative magnetic resonance imaging. Psoas cross-sectional area was measured at the L4 upper endplate and the level of surgery. Clinical outcomes were analyzed through standardized Oxford motor examinations, standardized sensory examinations, and patient-reported symptoms as documented and reviewed by the attending surgeon.Results: Eight hundred sixty-five patients underwent LLIF, of which 108 patients met inclusion criteria for imaging and indication (48 male, 60 female). The mean follow-up for included patients was 2.8 years (range 3.8 months-7.3 years). We observed a statistically significant mean decrease of 6.3% in psoas size on the surgical side (P < 0.001, Cohen's d = 0.19) and no significant change on the non-surgical side (P = 0.20, d = 0.07), both reflecting inconsequential effect sizes. Average hip flexor strength decreased by ≥ 1 grade in 8 (14.5%) patients on the surgical side and 5 patients (9.1%) on the nonsurgical side, with no significant difference between groups (P = 0.85).Discussion and conclusions: Our study found that LLIF was associated with minor long-term decreases in psoas size and quality on the surgical side, small mean bilateral strength losses, and no side-specific sensory deficits. 0 0 0 0