OBJECTIVES It is controversial whether to stop the fusion at L5 or S1 in adult spinal deformity (ASD) surgery. Our hypothesis is that we can stop long fusion at L5 for selected patients with less severe disability and less complex deformity. Aim was to compare minimum 5-year outcomes between ASD patients with fusion to L5 versus S1. PATIENTS AND METHODS Consecutive 40 patients (≥50 years of age) with ASD underwent spinal fusion from lower thoracic spine to L5 or S1 between 2008 and 2011. 33 patients (82.5 %) had a minimum 5-year follow-up. Lower instrumented vertebra (LIV) was L5 in 12 patients (L5 group) and S1 in 21 (S1 group). Clinical and radiographical parameters were compared between L5 and S1 group. RESULTS There were statistically significant differences between two groups (L5 vs S1) in %male (50 % vs 14 %), %type-N of SRS-Schwab classification (83 % vs 38 %), preop ODI (40.5 vs 56), correction loss of LL (11˚ vs 3˚), final TK (32˚ vs 50˚), correction loss of TK (-1˚ vs 17˚), final improvement of PT (3˚ vs 10˚), final improvement of PI-LL (26˚ vs 39˚), PJK (8% vs 48 %), and revision surgery rate (50 % vs 14 %). Causes of revision surgery in L5 group were distal junctional failure in 5 patients and foraminal stenosis at L5-S1 in 1. All of them underwent additional spinal fusion to the sacrum. Whereas, causes of revision surgery in S1 group were rod fracture in 2 patients and proximal junctional failure in 1. CONCLUSION Although fusion to L5 was conducted for selected ASD patients with less severe disability (better ODI) and less complex deformity (type N), 50 % of the patients required additional fusion to the pelvis. Decision making to stop the long fusion at L5 for ASD patients ≥50 years of age should be made with careful considerations.

中文翻译：

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我们是否可以停止 L5 的长融合术，用于选定的具有较轻残疾和不太复杂畸形的成年脊柱畸形患者？

目的 在成人脊柱畸形 (ASD) 手术中，是否在 L5 或 S1 处停止融合是有争议的。我们的假设是，对于残疾程度较轻且畸形较不复杂的选定患者，我们可以在 L5 处停止长融合。目的是比较融合到 L5 与 S1 的 ASD 患者之间的最短 5 年结果。患者和方法 2008 年至 2011 年期间，连续 40 名 ASD 患者（≥50 岁）接受了从下胸椎到 L5 或 S1 的脊柱融合术。33 名患者（82.5%）进行了至少 5 年的随访。12 名患者（L5 组）的下固定椎（LIV）为 L5，21 名患者（S1 组）为 S1。比较 L5 和 S1 组的临床和影像学参数。结果 两组（L5 与 S1）之间的男性百分比（50 % 与 14 %）存在统计学显着差异，SRS-Schwab 分类的 %type-N（83 % 对 38 %），术前 ODI（40.5 对 56），LL 的校正损失（11° 对 3°），最终 TK（32° 对 50°），校正损失为TK（-1˚ vs 17˚）、PT 最终改善（3˚ vs 10˚）、PI-LL 最终改善（26˚ vs 39˚）、PJK（8% vs 48 %）和翻修手术率（ 50% 对 14%）。L5组翻修手术原因为远端连接失败5例，L5-S1椎间孔狭窄1例，均行骶骨附加脊柱融合术。而 S1 组翻修手术的原因是 2 名患者的杆断裂和 1 名近端连接失败。 结论 尽管对选择的具有较轻残疾（更好的 ODI）和不太复杂的畸形（N 型）的 ASD 患者进行了 L5 融合， 50% 的患者需要额外的骨盆融合。