Analyzing the L4-5 Segmental Alignment Change of Two Minimally Invasive Prone-Based Interbody Fusions.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVE: Restoration of lumbar lordosis (LL) is a principal objective during spinal fusion procedures, traditionally focusing on achieving an LL within 10° of the pelvic incidence (PI). Recent studies have demonstrated a relatively constant L4-S1 alignment of 35-40° at L4-S1 and at least 15° at L4-5, regardless of PI. Based on these results, this study was created to examine the success rate of achieving a minimum of 15° at L4-5 through two differing prone-based techniques: Prone Lateral (pLLIF) and Trans Foraminal Interbody Fusion (TLIF). METHODS: One hundred patients with a primary single-level L4-5 interbody fusion (50 pLLIF and 50 TLIF) were retrospectively analyzed. Pre and post-operative radiographs were measured to examine the segmental change at each level in the lumbar spine and calculate the success rate for achieving a minimum L4-5 segmental lordosis of 15° at the final follow-up. RESULTS: The overall success rate of achieving an L4-5 segmental alignment >15° at the final follow-up was 70%. Prone LLIF was significantly more likely than TLIF to achieve this goal, achieving L4-5 > 15° 84% of the time vs TLIFs 56% (P = 0.002). Prone LLIF demonstrated an average L4-5 increase of 5.6 ± 5.9° which was larger than the mean increase for TLIF 0.4 ± 3.8° (P < 0.001). In both techniques, there was an inverse correlation between pre-operative L4-5 angle and L4-5 angle change. CONCLUSION: Prone lateral lumbar interbody fusion demonstrates a high success rate for achieving a post-operative L4-5 angle >15° and achieves this at a higher rate than TLIF.

Single-Position Prone Lateral Lumbar Interbody Fusion Technique Guide: Surgical Tips and Tricks.

Lateral lumbar interbody fusion (LLIF) is a popular technique as it allows for the placement of a large interbody implant through a retroperitoneal, transpsoas working corridor. Historically, the interbody is placed with the patient in lateral decubitus and then repositioned to prone for the posterior instrumentation. While this has been an effective and successful technique, removing the interoperative flip would improve the efficiency of these cases. This has led to modified LLIF approaches including single-position prone LLIF (pLLIF). This modification has shown to be an efficient and powerful technique; however, learning to navigate the LLIF approach in the prone position has its own challenges. The purpose of this article is to provide a detailed description of our pLLIF technique while simultaneously introducing surgical tips to overcome the challenges of the approach and optimize the implantation of the interbody device.

A retrospective review of single-position prone lateral lumbar interbody fusion cases: early learning curve and perioperative outcomes.

PURPOSE: The objective of this study was to discuss our experience performing LLIF in the prone position and report our complications. METHODS: A retrospective chart review was conducted that included all patients who underwent single- or multi-level single-position pLLIF alone or as part of a concomitant procedure by the same surgeon from May 2019 to November 2022. RESULTS: A total of 155 patients and 250 levels were included in this study. Surgery was most commonly performed at the L4-L5 level (n = 100, 40%). The most common preoperative diagnosis was spondylolisthesis (n = 74, 47.7%). In the first 30 cases, 3 surgeries were aborted to an MIS TLIF. Complications included 3 unintentional ALL ruptures (n = 3/250, 1.2%), and 1 malpositioned implant impinging on the contralateral foramen requiring revision (n = 1/250, 0.4%), which all occurred within the first 30 cases. Out of 147 patients with more than 6-week follow-ups, there were 3 cases of femoral nerve palsy (n = 3/147, 2.0%). Two cases of femoral nerve palsy improved to preoperative strength by the 6th week postoperatively, while one improved to 4/5 preoperative strength by 1 year. There were no cases of bowel perforation or vascular injury. CONCLUSION: Our single-surgeon experience demonstrates the initial learning curve when adopting pLLIF. Thereafter, we experienced reproducibility in our technique and large improvements in our operative times, and complication profile. We experienced no technical complications after the 30th case. Further studies will include long-term clinical and radiographic outcomes to understand the complete utility of this approach.