4 - A Comparison of Modern-era Anterior Lumbar Interbody Fusion and Transforaminal Lumbar Interbody Fusion at the Lumbosacral Junction

Introduction: Interbody fusion is the primary method for achieving arthrodesis across the lumbosacral junction in the setting of degenerative pathologies, such as spondylosis and spondylolisthesis. Two common techniques are anterior lumbar interbody fusion (ALIF) and posterior transforaminal lumbar interbody fusion (TLIF).

Objective: This study compares changes in radiographic and clinical parameters between patients undergoing modern-era single-level ALIF and minimally invasive (MIS) TLIF at L5-S1.

Methods: Consecutive patients who underwent single-segment L5-S1 ALIF or MIS TLIF at a over a 5-year interval were retrospectively reviewed. Upright radiographs were used to determine pre- and postoperative lumbar lordosis, segmental lordosis, disc angle, and neuroforaminal height. Improvements in patient-reported outcome scores (ODI and SF-36) were also compared.

Results: Overall, 108 patients (58 [54%] men, 50 [46%] women; mean [standard deviation] age, 57.6 [13.5] years) were included in the study. ALIF was performed for 49 patients, and TLIF was performed for 59 patients. The most common treatment indications were spondylolisthesis (50% [54/108]) and spondylosis (46% [50/108]). The cohorts did not differ in terms of intraoperative (p>0.99) or postoperative (p=0.73) complication rates. Mean (standard deviation) hospital length of stay was significantly shorter for patients undergoing TLIF than ALIF (1.3 [0.6] days vs. 2.0 [1.4] days, p< 0.001). Both techniques achieved significant improvements in L5-S1 segmental lordosis, disc angle, and neuroforaminal height (p≤0.008). ALIF versus TLIF resulted in significantly greater mean increases in segmental lordosis (12.5° [7.3°] vs. 2.1° [5.7°], p< 0.001), disc angle (14.8° [5.5°] vs. 3.1° [6.2°], p< 0.001), and neuroforaminal height (4.5 [4.6] mm vs. 2.4 [3.0] mm, p=0.008). Improvements in patient-reported outcome parameters were similar between cohorts.

Conclusions: When treating patients at a single segment across the lumbosacral junction, ALIF resulted in significantly greater increases in segmental lordosis, L5-S1 disc angle, and neuroforaminal height compared to MIS TLIF. Improvements in clinical parameters were similar between the 2 techniques.