Importance of Preoperative Evaluation for LLIF

Preoperative evaluation is critical to the safety, efficacy, and outcomes of lateral lumbar interbody fusion (LLIF). Thorough assessment of patient-specific anatomy, pathology, and comorbidities enables optimal surgical planning, minimizes complications, and guides appropriate approach selection. LLIF encompasses the transpsoas and anterior-to-psoas (oblique) corridors, each with distinct anatomical and technical considerations. Detailed preoperative imaging assesses corridor dimensions, psoas morphology, vascular proximity, and neural structures, such as the lumbar plexus and sympathetic chain. Anatomical variations, including the “rising psoas” sign or limited retroperitoneal space, may contraindicate certain approaches. Understanding vascular, visceral, and retroperitoneal anatomy is essential to prevent injury to segmental vessels, the ureter, and other critical structures. Patient selection should consider clinical indications, exclusion criteria, and cautionary factors, including severe central stenosis, facet arthropathy, or osteoporosis. Recognition of factors predicting indirect decompression failure—such as multilevel disease, uncontained disc herniations, or chronic severe radiculopathy—supports tailored surgical strategies, potentially incorporating staged or supplementary posterior procedures. Comprehensive preoperative evaluation ensures that LLIF remains a safe, minimally invasive, and motion-preserving technique, capable of addressing diverse lumbar pathologies while reducing morbidity and optimizing long-term results.