L4-L5 anatomy classification system for lateral lumbar interbody Fusion

Abstract

Abstract Introduction: Lateral lumbar interbody fusion (LLIF), developed by Dr. Luiz Pimenta in 2006, allows access to the spinal column through the psoas major muscle. The technique has many advantages, such as reduced bone and muscular tissue damage, indirect decompression, larger implants, and lordosis correction capabilities. However, this technique also has drawbacks, with the most notorious being the risk of spinal pathologies due to indirect injury of the lumbar plexus, but with low rates of persistent injuries. Therefore, several groups have proposed classifications to help identify patients at a greater risk of presenting with neurological deficits. The present work aims to propose a new classification system that relies on the simple observation of easily identifiable key structures to guide lateral L4-L5 LLIF decision-making. Methods: Patients aged > 18 years who underwent preoperative magnetic resonance imaging (MRI) were included. This came to the office between 2022 and 2023 until 50 quality images were acquired. And excluded as follow Anatomical changes in the vertebral body or major psoas muscles prevent the identification of key structures or poor-quality MRIs. Each anatomy was classified as type I, type II, or type III according to the consensus among the three observers. Results: Fifty anatomical sites were included in this study. Seventy percent of the L4-L5 anatomy were type I, 18% were type II, and 12% were type III. None of the type 3 L4-L5 anatomies were approached using a lateral technique. Conclusion: The proposed classification is an easy and simple method for evaluating the feasibility of a lateral approach to–L4-L5.