Objective: To investigate whether the upper instrumented vertebra (UIV) can be selected at one level caudal to upper end vertebra (UEV) in Lenke type 5C adolescent idiopathic scoliosis (AIS) patients. Methods: Total of 28 Lenke 5C AIS patients who underwent selective posterior fusion in Drum Tower Hospital of Nanjing University Medical School from September 2013 to September 2015 were included. There were 4 males and 24 females, with an age of (15.0±2.0) years, the Risser sign was graded 2-5. The following imaging parameters were measured on standing full spine X-ray before, immediately after the surgery and at the last follow-up: thoracolumbar/lumbar (TL/L) Cobb angle, coronal balance, UIV translation, lower instrumented vertebra (LIV) translation, UIV tilt, LIV tilt, and thoracic apical vertebral translation (T-AVT), lumbar apical vertebral translation (L-AVT). The patients were divided into two groups: decompensation group (n=6) and non-decompensation group (n=22). Radiographic parameters and Scoliosis Research Society (SRS)-22 scores were compared between the two groups. Results: Six cases (21.4%) had proximal decompensation at the last follow-up. There were no significant differences in Risser grade(3.8±1.0 vs 3.6±1.6), baseline thoracic Cobb angle(25.8°±2.2° vs 26.3°±6.4°) and TL/L Cobb angle(43.7°±3.4° vs 45.2°±6.5°) between the two groups (all P>0.05). However, the baseline lumbar/thoracic apical vertebra translation (L-T AVT ratio) was significantly higher in patients with proximal decompensation (6.3±1.3 vs 4.0±2.0, P=0.048). Conclusion: Selecting UIV at one level caudal to UEV, would not increase the incidence of proximal decompensation in Lenke 5C AIS patients with Risser higher than grade 2, the smaller baseline L-T AVT ratio, and with thoracic compensatory curve over 15°, and can obtain satisfactory clinical results.

目的： 探讨Lenke 5C型青少年特发性脊柱侧凸（AIS）后路矫形时是否可以将上固定椎（UIV）选择在上端椎（UEV）下方一个椎体。 方法： 前瞻性纳入2013年9月至2015年9月于南京鼓楼医院行选择性后路融合的Lenke 5C型AIS患者28例，其中男4例，女24例，年龄为（15.0±2.0）岁；Risser征2~5级。所有患者术前、术后和末次随访均摄站立位全脊柱正侧位X线片，测量下列影像学参数：胸弯、腰弯Cobb角、UIV和下固定椎（LIV）的偏移（translation）及倾斜角（tilt）、胸弯和腰弯顶椎偏移（AVT）、冠状面平衡。根据末次随访时患者是否出现近端失代偿分为失代偿组和未失代偿组。比较两组患者的影像学参数和脊柱侧凸研究协会问卷（SRS-22）评分。 结果： 6例（21.4%）患者在末次随访时出现近端失代偿。失代偿与无失代偿两组患者的Risser分级（3.8±1.0比3.6±1.6）、术前胸弯Cobb角（25.8°±2.2°比26.3°±6.4°）、主弯Cobb角（43.7°±3.4°比45.2°±6.5°）差异均无统计学意义（均P>0.05）。然而，近端失代偿患者的术前腰弯/胸弯顶椎偏移比值（L-T AVT）显著较大（6.3±1.3比4.0±2.0，P=0.048）。 结论： 对于Lenke 5C型AIS患者，若术前胸弯Cobb角>15°，Risser>2级，术前腰弯/胸弯顶椎偏移比值较小，可将UIV设计为UEV下方一个椎体，并不增加近端失代偿风险却可获得满意效果。.