Is Anchored Stand-Alone ALIF Effective and Safe for the Treatment of Low-Grade L5-S1 Isthmic Spondylolisthesis? A Comparative Study With Posterior Lumbar Interbody Fusion

Study Design: Retrospective comparative study. Objectives: Optimal surgical treatment for low-grade L5-S1 isthmic spondylolisthesis (IS) is still subject of debate. While various surgical approaches exist, anchored stand-alone (SA) ALIF has emerged as a promising alternative technique. This study aimed to compare the efficacy, as well as the clinical and radiological outcomes of anchored SA-ALIF and posterior lumbar interbody fusion in the management of low-grade L5-S1 IS. Methods: A total of 53 patients, 26 from the anterior group and 27 from the posterior group, met the inclusion criteria. Intraoperative blood loss, operative time, radiation exposure and postoperative length of hospitalization were retrospectively evaluated. Clinical outcomes were assessed using the ODI and VAS scales. Upright lumbosacral X-ray and lumbosacral CT scan were used to evaluate spinopelvic parameters and intersomatic fusion according to Brantigan-Steffee-Fraser (BSF) scale, respectively. Results: The mean postoperative follow-up was 39 months. Intraoperative blood loss, radiation exposure, operative time, and postoperative length of hospitalization were significantly lower in the anterior group. Effective ODI and VAS improvement was achieved in both anterior and posterior groups. No significant differences were observed between the two groups in postoperative spinopelvic parameters assessment. Effective spinal fusion was achieved in 23 patients (88.4%) in the anterior group, and in 21 patients (77.8%) in the posterior group. Conclusion: While both techniques effectively achieve spinal fusion and symptom relief, anchored SA-ALIF offers significant advantages over posterior fusion techniques in terms of intraoperative blood loss, radiation exposure, operative time, and postoperative length of hospitalization.