目的:探讨退变性脊柱侧凸（degenerative scoliosis，DS）接受经骶2骶髂螺钉（second sacralalar-iliac，Sn 2AI）固定术后随访期间骨盆入射角（pelvic incidence，PI）的变化，并分析与PI变化的可能相关因素。n 方法:回顾性分析自2014年11月至2017年1月期间80例接受Sn 2AI螺钉固定技术进行骨盆固定，且至少随访2年的DS患者病历资料，男30例（37.5%）、女50例（62.5%），年龄为（55.3±16.2）岁（范围38~73岁），随访时间为（34.6±8.7）个月（范围24~96个月）。根据术后即刻PI的变化将患者分为两组：PI降低5°（PI活动组），共49例，男1例（2.0%）、女48例（98.0%），年龄（51.7±12.9）岁。在手术前后及术后2年测量以下影像学参数：PI、腰椎前凸角（lumbar lordosis，LL）、骨盆倾斜角（pelvictilt，PT）、PI-LL、脊柱矢状面平衡（sagittal vertical axis, SVA）。临床疗效评价采用脊柱侧凸研究学会-22简明量表调查问卷（Scoliosis Research Society questionnaires-22，SRS-22），并记录患者术中及术后随访期间的并发症发生情况。比较两组患者随访期间PI的变化情况。n 结果:两组患者在年龄、性别、术前影像学参数及SRS-22的差异均无统计学意义（n P>0.05）。术后PI稳定组31例（38.8%），PI从45.7°±11.4°降至45.3°±11.2°，差异无统计学意义；另49例（61.2%）为PI活动组，PI从51.6°±14.5°下降至40.9°±14.0°。末次随访时PI活动组中24例（49%）PI恢复（PI恢复组），增加幅度>5°；余25例（51%）无增加（PI保持组），平均ΔPI变化为-4.2°。分层分析显示PI恢复组与PI保持组的ΔPI、术后PI、术后PT和年龄的差异均有统计学意义。术前PI、术后PI、术后PT、术后PI-LL与末次随访时的ΔPI明显相关。Logistic回归分析显示术后PI是相关因素（n OR=0.87，n P=0.024）。n 结论:DS患者应用Sn 2AI螺钉固定技术进行骨盆固定术后即刻超过50%患者会发生PI下降，在术后至少2年的随访期间发生PI明显改变的患者中49%的患者存在PI恢复。较低的术前PI、术后PI和PT与PI的恢复密切相关。n “,”Objective:To investigate how pelvic incidence (PI) would change during the follow-up in degenerative scoliosis (DS) patients who underwent second sacralalar-iliac (Sn 2AI) fixation and identify the possible factors associated with the changes in PI.n Methods:The DS patients who underwent long fusion to pelvis with Sn 2AI fixation with a minimum follow-up of two years between November 2014 to January 2017 were retrospectively reviewed in this study. The following sagittal radiographic parameters were measured, including pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt (PT), PI minus LL (PI-LL), and sagittal vertical axis (SVA) at pre-operation, post-operation and 2-year follow-up. Patients were divided into two groups at immediate post-operation: PI decreased less than 5° or increased (Group PI stabilization); PI decreased larger than 5° (Group PI activity). Descriptive statistics were calculated for all patients in the form of mean value and standard deviation (SD). Comparisons of means between variables were performed using an unpaired Student\'s t test. Pearson correlation coefficienttest was performed to determine the correlations between all radiographic variables. Inter- and intra-observer reliability was assessed using intraclass correlation coefficient (ICC). The internal consistency of the measurements was characterized as excellent (n ICC≥0.9), good (0.7≤n ICC<0.9), acceptable (0.6