1614. Lateral Lumbar Interbody Fusion (LLIF) for Adjacent Segment Disease (ASD): Outcomes and Decision Tree Analysis

Authors: Zachary S. Hubbard, MD; Karthik Madhaven, MD; Lee Onn Chieng, MD; Seth Williams, MD; Steven Vanni, DO (Charleston, SC)

Introduction Adjacent level disease (ASD) is a known complication of lumbar spine fusion. ASD is often managed by posterior approach with fusion and has shown to have good outcomes. Recently, lateral lumbar interbody fusion (LLIF) has gained popularity for its minimally invasive approach. Methods We performed a retrospective chart analysis of all the patients who underwent lateral interbody fusion (LLIF) since 2006 and identified 46 patients specifically treated with LLIF for adjacent level disease. We evaluated outcomes and performed a decision tree analysis. Statistics were carried out using SPSS 22. Results 46 patients were treated with LLIF for ASD including 24 females and 22 males, the average age of the patients was 63.15 ±10.07 years and the mean follow up period was 18.5 months. LLIF was performed on the L1-L2 level in 6 patients, L2-L3 in 26, L3-L4 in 18, L4-L5 in 4 and L5-S1 in 1. Radiographic fusion was achieved in 45 (92%) of patients. There was significant intervertebral disc height restoration from a mean preoperative value of 8.24 ± 2.72mm to 12.39 ± 2.08mm (p < 0.0001). Global impression of change was improved in the back in 37/42 patients and in the legs in 35/39 patients. 15 patients developed complications. Four patients developed pseudoarthrosis and five developed subsequent ASD. The best predictors of complications were change in intervertebral height <0.69 cm and age greater than 49. The best predictors of subsequent ASD were LLIF performed at L4-L5 in nonsmokers and change in intervertebral height <0.69 cm when LLIF is performed at L3-L4. The best predictor for pseudoarthrosis formation was an active smoking status. Of the former and nonsmokers, those with global lordosis change greater than 16 degrees has a 50% rate of pseudoarthrosis. Conclusion LLIF is a feasible alternative treatment modality for ASD.