Access to L1–L2 and L2–L3

Minimally invasive surgical (MIS) access to the upper lumbar segments (L1–L2, L2–L3) is largely limited to oblique (prepsoas) and lateral (transpsoas) approaches due to the presence of the great vessels anteriorly. Unlike the most caudal lumbar segments, in which mini-open anterior approaches are feasible, the L1–L2 and L2–L3 levels are more safely and effectively accessed via a lateral approach. Advantages of a minimally invasive lateral lumbar transpsoas approach include the ability to place large interbody grafts, preservation of the facet joints and posterior tension band, and approach execution without an access surgeon. Awareness of the position of the lumbar plexus at each segment is key to safe execution of this technique, and much prior research has been performed to establish safe working zones based on anatomic level. Similarly, patient positioning is critical to allow for optimal radiographic images intraoperatively and to minimize technical challenges with instrumentation.