Does Additional Distal S2 Fixation Improve Lumbosacral Stability Compared with Standard L4-S1 Fixation in High-Grade Spondylolisthesis? A Prospective Randomised Comparative Study.
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引用次数: 0
Abstract
Study design: Prospective, randomised, single-centre comparative study.
Objective: To compare standard L4-S1 fixation with an identical construct extended by bilateral S2 fixation in patients undergoing posterior lumbar interbody fusion for high-grade L5-S1 spondylolisthesis.
Summary of background data: High-grade L5-S1 spondylolisthesis subjects posterior fixation to lumbosacral shear that may exceed the tolerance of a standard L4-S1 construct. Extending fixation distally to S2 - using either a conventional S2 pedicle screw or, where sacral purchase is inadequate, an S2 alar-iliac (S2AI) screw - has been proposed to mitigate this shear, but comparative prospective data remain limited.
Methods: Seventy consecutive patients with Meyerding grade III/IV spondylolisthesis undergoing posterior lumbar interbody fusion between May 2020 and November 2022 were randomly allocated 1:1 to standard L4-S1 fixation (Group A, n=35) or bilateral S2 extension (Group B, n=35; conventional S2 pedicle screws in 29, intraoperative conversion to S2-alar-iliac fixation in 6). Co-primary outcomes were the Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) at 36 months, compared using a Bonferroni-adjusted significance threshold.
Results: All 70 patients (100%) completed follow-up. Group B achieved lower VAS (1.9±0.8 vs. 3.1±1.0, P<0.001) and ODI (21.4±5.6 vs. 30.1±6.0, P<0.001). Fusion rate (88.6% vs. 77.1%, P=0.34), pseudarthrosis (11.4% vs. 22.9%, P=0.34), and screw pull-out (2.9% vs. 14.3%, P=0.20) all numerically favoured Group B without reaching statistical significance. S1 screw breakage occurred exclusively in Group A (65.7% vs. 0%, P<0.001).
Conclusions: These findings suggest that distal fixation, through S2 or S2AI, may play a substantial role in mitigating the shear stress forces at the lumbosacral junction and the hardware failures commonly seen with S1-only anchorage in this complex pathology. Given the potential for performance bias and technique heterogeneity (conventional S2 vs. S2AI), multicentre randomised trials are warranted to confirm these findings and define which patients benefit most from S2 extension.
研究设计：前瞻性、随机、单中心比较研究。目的：比较标准L4-S1固定与双侧S2固定扩展相同结构在后路腰椎椎间融合术治疗高度L5-S1腰椎滑脱患者中的应用。背景资料总结：高度L5-S1椎体滑脱患者后路固定腰骶切变，可能超过标准L4-S1结构的容忍度。已提出将固定扩展到远端S2 -使用传统的S2椎弓根螺钉或在骶骨购买不足时使用S2翼髂（S2AI）螺钉-以减轻这种剪切，但比较前瞻性的数据仍然有限。方法：在2020年5月至2022年11月期间，连续70例Meyerding III/IV级腰椎滑脱患者行后路腰椎椎间融合术，随机按1:1分配至标准L4-S1固定组（A组，n=35）或双侧S2延伸组（B组，n=35）； 29例采用常规S2椎弓根螺钉，6例术中转换为S2-髂椎弓根固定。共同主要结局是视觉模拟量表（VAS）和36个月时的Oswestry残疾指数（ODI），使用bonferroni调整显著性阈值进行比较。结果：70例患者全部（100%）完成随访。B组的VAS较低（1.9±0.8 vs. 3.1±1.0）。结论：这些发现表明，通过S2或S2AI进行远端固定，可能在减轻腰骶连接处的剪切应力和在这种复杂病理中仅使用s1锚固时常见的硬件故障方面发挥了重要作用。考虑到潜在的表现偏倚和技术异质性（传统S2 vs. S2AI），有必要进行多中心随机试验来证实这些发现，并确定哪些患者从S2扩展中获益最多。
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Recognized internationally as the leading journal in its field, Spine is an international, peer-reviewed, bi-weekly periodical that considers for publication original articles in the field of Spine. It is the leading subspecialty journal for the treatment of spinal disorders. Only original papers are considered for publication with the understanding that they are contributed solely to Spine. The Journal does not publish articles reporting material that has been reported at length elsewhere.
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