Is Anterior Column Release (ACR) more effective than Pedicle Subtraction Osteotomy (PSO) in primary Adult Spinal Deformities? A systematic Review and Meta-analysis

Introduction: Treating Adult Spinal Deformity (ASD) is pivotal in spine surgery, but the best method is debatable. Traditionally, Pedicle Subtraction Osteotomy (PSO) corrects sagittal and coronal deformities, yet Anterior Column Release (ACR) offers a minimally invasive option. We aimed to determine if ACR outperforms PSO in clinical and radiological outcomes.

Methods: We conducted a systematic review of English-language studies on the surgical management of primary Adult Spinal Deformity (ASD) using the PubMed database. We utilized search terms such as 'ACR,' 'PSO,' 'lordosis,' 'pelvic incidence,' 'sagittal vertical axis,' and 'T1-pelvic-angle.' Exclusions comprised case reports, studies with fewer than 10 patients, cadaveric studies, literature reviews, and pediatric populations. We also excluded studies involving both PSO and ACR in the same setting, different osteotomies, or deformities secondary to adjacent segment disease. Data extraction and analysis were conducted manually using R version 4.3.1.

Results: The PRISMA protocol was used. The Authors found 19 retrospective clinical studies with a total of 771 patients; among them, 234 received ACR and 537 received PSO. The weighted mean age was 65.09±6.32 for ACR and 63.61±10.35 for PSO. The pooled mean difference of pre and post operative ODI score for ACR was -21.19 (CI 95% [ -46.35, 3.97]), while for PSO was -19.7 (CI 95% [-36.57, -2.83]). Regarding pre and post operative PI-LL mismatch reduction, the pooled mean difference was -16.89 (CI 95% [-37.27, 3.49]) for ACR and -30.15 (CI 95% [-41.54, -18.76]) for PSO. The post operative PI-LL mismatch difference between ACR and PSO showed a pool mean difference of 7.75 (CI 95% [-122.49, 137.98]). For adverse effects, the pooled frequency was 0.18 (CI 95% [0.11, 0.28]) for ACR and 0.33 (CI 95% [0.13,0.63]) for PSO.

Conclusion : The findings from this meta-analysis indicate that ACR results in a superior post-operative ODI while PSO is more effective in correcting the deformity. However, this comes at the cost of a higher rate of complications.