Neurological Complications After Lateral Lumbar Interbody Fusion: Incidence, Patterns, and Risk Factors in a 545-Patient Cohort

Introduction: Lateral lumbar interbody fusion (LLIF) provides effective anterior column reconstruction while avoiding extensive posterior dissection; however, its transpsoas trajectory places the lumbar plexus at risk of neurological complications. The incidence, clinical patterns, and predictors of these events remain incompletely defined because of heterogeneous reporting across studies. Method: We performed a retrospective cohort study of consecutive adult patients undergoing transpsoas LLIF at a tertiary spine centre between 2016 and 2023. Demographic, clinical, and operative variables were collected, and postoperative neurological complications were identified from clinical documentation and imaging when available. Multivariable logistic regression was performed to determine independent predictors of transient motor weakness, acute thigh paraesthesia, and transient paraesthesia. Results: Among 545 patients, 167 (30.6%) experienced at least one neurological complication. The most common events were acute thigh paraesthesia (14.4%) and transient motor weakness (13.2%), whereas hip flexion weakness (2.1%), femoral palsy (1.3%), and psoas haematoma (1.4%) were uncommon. Obesity was independently associated with transient motor weakness (OR 1.77, 95% CI 1.06–2.93; p = 0.028). Younger age independently predicted acute thigh paraesthesia (OR 0.96 per year, 95% CI 0.94–0.99; p = 0.002) and transient paraesthesia (OR 0.97 per year, 95% CI 0.94–1.00; p = 0.049). Multilevel surgery was independently associated with acute thigh paraesthesia (OR 1.67, 95% CI 1.02–2.74; p = 0.043). Conclusions: Neurological complications following LLIF are relatively frequent but are predominantly transient sensory disturbances or temporary motor weakness. Obesity, younger age, and multilevel surgery identify patients with increased risk of specific neurological events. These findings support individualized counselling, careful surgical planning, and continued investigation into anatomical and intraoperative factors underlying LLIF-related neurological morbidity.