LAUSR

PURPOSE Lateral lumbar interbody fusion (LLIF) at the L4/5 level is a controversial topic in the spine literature. The aim of this study was to compare the rate of nerve-related motor deficits in patients undergoing LLIF with and without L4/5 involvement. METHODS Clinical data of consecutive patients undergoing LLIF between 2006-2016 at a single academic institution were retrospectively reviewed for new postoperative motor weakness of the quadriceps or tibialis anterior muscle. Patients were divided into two groups according to L4/5 involvement. Regression analysis was performed to examine the association of LLIF at L4/5 and the risk of new motor deficits. RESULTS A total of 872 patients met inclusion criteria. The rate of new motor deficits at the 6 week postoperative visit in the L4/5 group was 13.1%, which was significantly higher compared to the non-L4/5 group with 5.5% (p<0.001). After adjusting for potential confounders in multivariate logistic regression models, L4/5 was still significantly associated with an increased risk for new motor deficit (OR = 2.290; p=0.008). Among 686 patients with minimum follow-up of 6 months, persistent nerve-related motor deficits at last follow-up were recorded in 2.5% in the L4/5 group and 0.4% in the non-L4/5 group (p=0.065). CONCLUSIONS The results of this large study are in line with previous investigations which report an initial increased risk of new motor deficits for LLIF performed at L4/5. However, the majority of new motor deficits was transient in nature and resolved over time.