骨盆入射角与腰椎前凸角匹配度对强直性脊柱炎后凸畸形矫形术后矢状面平衡的影响

Effect of mismatch between pelvic incidence and lumbar lordosis on sagittal imbalance of ankylosing spondylitis following kyphosis correction

中文关键词:  强直性脊柱炎  后凸畸形  骨盆入射角与腰椎前凸角匹配度  矢状面失衡  截骨矫形术

英文关键词:Ankylosing spondylitis  Kyphosis  Pelvic incidence and lumbar lordosis mismatch  Sagittal imbalance  Osteotomy

中文摘要:

  【摘要】 目的：探讨骨盆入射角与腰椎前凸角匹配度（pelvic incidence and lumbar lordosis mismatch，PI-LL）对强直性脊柱炎（ankylosing spondylitis，AS）后凸畸形矫形术后脊柱骨盆矢状面平衡的影响。方法：回顾性研究2010年1月~2019年10月本团队行改良经椎弓根椎体截骨术治疗的85例AS后凸畸形患者，男75例，女10例；年龄37.1±8.8岁（20~67岁），其中63例行单节段截骨矫形，22例行双节段截骨矫形。脊柱全长侧位片上测量术前、术后（3~4周）及末次随访时脊柱骨盆矢状面参数：骨盆入射角（pelvic incidence，PI）、骨盆倾斜角（pelvic tilt，PT）、骶骨倾斜角（sacral slope，SS）、腰椎前凸角（lumbar lordosis，LL）、PI-LL、截骨角（osteotomized vertebral angle，OVA）和矢状面躯干偏移（sagittal vertical axis，SVA）。术前及末次随访时采用脊柱侧凸研究学会-22（Scoliosis Research Society-22，SRS-22）问卷和Oswestry功能障碍指数（Oswestry disability index，ODI）评估患者的肢体功能和生活质量。末次随访时SVA>5cm为脊柱矢状面失衡，PT>25°为骨盆矢状面失衡。通过Pearson相关系数分析术后PI-LL与末次随访SVA和PT的相关性，并运用受试者操作特征（receiver operating characteristic，ROC）曲线和最大约登指数计算术后PI-LL的阈值，获得PI-LL的最佳匹配度。根据术后PI-LL是否满足最佳匹配度分组，分析不同术后PI-LL对末次随访脊柱骨盆矢状面序列的影响。运用线性回归分析腰椎OVA与PI-LL矫正值的线性关系，计算线性回归方程。结果：85例AS患者术后平均随访30.8±6.3个月（24~84个月），末次随访时LL（-31.6°）、PT（31.8°）、SS（15.5°）、PI-LL（16.7°）和SVA（8.6cm）均较术前明显改善（P<0.05），ODI（23.45%）和 SRS-22（3.91分）评分显著性优于术前（P<0.05）。术后PI-LL与末次随访时的SVA和PT呈显著性正相关（r=0.525和0.659，P<0.01）。以末次随访时SVA为状态变量, 通过ROC曲线分析获得术后PI-LL的阈值为12.8°；以末次随访时的PT为状态变量，计算得到术后PI-LL的阈值为10.5°。当术后PI-LL≤10.5°时，可同时满足预防脊柱和骨盆矢状面失衡的要求。与术后PI-LL＞10.5°组比较，术后PI-LL≤10.5°组患者末次随访时PT（25.4° vs 36.6°）、LL（-40.8° vs -24.1°）、PI-LL（4.0° vs 26.2°）和SVA（5.6cm vs 10.9cm）更小（P<0.05），脊柱（36.1% vs 75.5%）和骨盆（38.9% vs 85.7%）矢状面失衡率更低（P<0.05）。腰椎OVA与PI-LL矫正值呈较高强度线性正相关（r=0.707，P<0.01），腰椎OVA=17.12+0.62×（PI-LL矫正值），R2=50.1%。结论：AS后凸畸形患者截骨矫形术后的PI-LL与末次随访SVA和PT紧密相关，术后重建PI-LL≤10.5°可维持良好的脊柱骨盆矢状面平衡，降低中远期随访脊柱和骨盆矢状面失衡的风险。

英文摘要:

  【Abstract】 Objectives: The current study aimed to investigate the effect of pelvic incidence and lumbar lordosis mismatch(PI-LL) on sagittal imbalance of ankylosing spondylitis(AS) following corrective osteotomy. Methods: 85 AS patients(75 men, 10 women) who underwent modified pedicle subtraction osteotomy(PSO) between January 2010 and October 2019 were enrolled in this study, with an average age of 37.1±8.8 years(20-67 years). 63 underwent one-level osteotomy, and 22 underwent two-level osteotomy. The preoperative, postoperative(3-4 weeks after surgery) and final follow-up radiographic parameters were measured, including pelvic incidence(PI), pelvic tilt(PT), sacral slope(SS), lumbar lordosis(LL), PI-LL, osteotomized vertebral angle(OVA), and sagittal vertical axis(SVA). The function of limbs and health-related quality of life before operation and at the final follow-up were evaluated using Scoliosis Research Society-22(SRS-22) patient questionnaire and Oswestry disability index(ODI). At the final follow-up, SVA>5cm was regarded as spinal imbalance, and PT>25° was considered pelvic imbalance. Correlations between postoperative PI-LL and final follow-up SVA and PT were analyzed using Pearson correlation coefficient. Threshold of PI-LL was figured out using receiver operating characteristic(ROC) curve and maximum Youden index to obtain the optimal postoperative PI-LL. Patients were divided into two groups by whether meeting the optimal postoperative PI-LL, and effects of different postoperative PI-LL on spino-pelvis sagittal alignment at the final follow-up were compared and evaluated. Subsequently, linear regression was used to evaluate the relationship between lumbar OVA and PI-LL correction to figure out the regression equation. Results: 85 AS patients were followed up for 30.8±6.3 months(24-84 months). The final follow-up LL(-31.6°), PT(31.8°), SS(15.5°), PI-LL(16.7°) and SVA(8.6cm) were improved significantly(P<0.05); and the final follow-up ODI(23.45%) and SRS-22 score(3.91) were better than those before surgery(P<0.05). Postoperative PI-LL positively correlated with the final follow-up SVA and PT(r=0.525 and 0.659 respectively, P<0.01). Calculated with SVA using ROC and maximum Youden index, the optimal threshold of postoperative PI-LL was 12.8°; while, calculated with PT, it was 10.5°. Postoperative PI-LL of ≤10.5° met the needs for preventing both spinal and pelvic imbalance. Patients with postoperative PI-LL≤10.5° had better PT(25.4° vs 36.6°), LL(-40.8° vs -24.1°), PI-LL(4.0° vs 26.2°) and SVA(5.6cm vs 10.9cm) than those with postoperative PI-LL>10.5°, and significantly deceased the rate of spinal (36.1% vs 75.5%) and pelvic(38.9% vs 85.7%) imbalance at the final follow-up(P<0.05). Lumbar OVA highly correlated with PI-LL correction(r=0.707, P<0.001), and the equation was Lumbar OVA=17.12+0.62×(PI-LL correction), adjusted R2=50.1%. Conclusions: Postoperative PI-LL strongly correlated with final follow-up SVA and PT in AS patients after kyphosis correction. Reconstructing postoperative PI-LL ≤10.5° could achieve better spino-pelvis sagittal alignment for AS kyphosis, and decrease the risk of spinal and pelvic imbalance in mid- to long-term follow-up.