强直性脊柱炎胸腰椎后凸畸形截骨矫形术后近端交界性后凸的危险因素与临床意义

Etiological analysis and clinical significance of proximal junctional kyphosis after osteotomy in ankylosing spondylitis-related kyphosis

目的 :探讨强直性脊柱炎(ankylosing spondylitis,AS)胸腰椎后凸畸形矫形术后发生近端交界性后凸(proximal junctional kyphosis,PJK)的危险因素及表现形式。方法 :回顾性分析2002年1月~2015年12月接受矫形手术且随访大于2年的133例AS胸腰椎后凸畸形患者,男性118例,女性15例,年龄35.1±9.8岁(18~63岁)。收集患者临床资料,包括年龄、性别、体重指数、截骨方式和椎体融合节段。术前、术后及每次随访拍摄全脊柱正侧位片,并测量矢状面平衡(sagittal vertical axis,SVA)、胸椎后凸角(thoracic kyphosis,TK)、腰椎前凸角(lumbar lordosis,LL)、骶骨倾斜角(sacral slope,SS)、骨盆倾斜度(pelvic tilt,PT)、骨盆投射角(pelvic incidence,PI)和近端交界角(proximal junctional angle,PJA)。根据PJA将患者分为PJK组和非PJK组,利用卡方检验及t检验对比两组间临床资料及影像学参数。结果:133例患者平均随访3.6±2.2年(2.0~15.0年),11例发生PJK,平均在术后随访3.7年(0.3~15.0年)发生,PJA从术前5.5°±9.7°进展至21.2°±9.5°。PJK组手术年龄低于非PJK组(P<0.01),PJK组行SPO人数比例高于非PJK组(P<0.01)。PJK组术前PJA和SVA均低于非PJK组(P<0.05)。两组间TK、LL、SS、PT和PI均无显著性差异(P>0.05)。11例PJK患者中,有3种PJK表现形式,包括假关节(2例)、压缩性骨折(3例)和AS胸椎后凸畸形的自然进展(6例)。末次随访时,1例假关节PJK患者自发性愈合,1例AS胸椎后凸畸形自然进展的PJK患者行翻修手术,其余患者均予以随访观察。结论:AS术后PJK表现形式包括假关节、压缩性骨折和AS胸椎后凸畸形的自然进展。初次手术年龄、手术方式、术前PJA及SVA影响PJK的发生。

Objectives： To investigate the risk factors and clinical features of proximal junctional kyphosis （PJK） after osteotomy in thoracolumbar kyphosis secondary to ankylosing spondylitis（AS）. Methods： A retrospective review of 133 AS patients with thoracolumbar kyphosis who underwent correction surgery between January 2002 and December 2015 with a minimum of 2-year follow-up performed, including 118 males and 15 females. The mean age was 35.1±9.8 years（range, 18-63 years）. Clinical data and radiographic parameters were assessed for the risk factors of PJK. Clinical data included age, sex, body mass index, types of osteotomy and fusion levels. Radiographic parameters were measured preoperatively, postoperatively and at each follow-up including sagittal vertical axis（SVA）, thoracolumbar kyphosis（TK）, lumbar lordosis（LL）, sacral slope（SS）, pelvic tilt（PT） and proximal junctional angle（PJA）. Patients were divided into PJK group and no PJK group according to the change in PJA. Comparison of clinical and radiographic data were performed between the 2 groups using Student′s t-test and Chi-square test. Results： Among the 133 patients with an average of 3.6±2.2 years（range, 2 to 15 years） follow-up, PJK was observed in 11 patients, at a mean of 3.7±4.1 years（range, 0.3 to 15 years） with PJA increased from 5.5°±9.7° preoperatively to 21.2°±9.5° at the time of PJK. Compared with the no PJK group, PJK group showed lower age（P〈0.01） and higher proportion of patients undergoing SPO（P〈0.01）. Preoperative PJA and SVA were greater in the no PJK group（P〈0.05）. There were no significant differences in TK, LL, SS, PT and PI between the two groups（P〉0.05）. There were 3 types of PJK, including pseudoarthrosis（n=2）, compression fracture（n=3） and progressing thoracic kyphosis due to the natural history of AS（n=6）. At final follow-up, spontaneous fusion of pseudoarthrosis was found in 1 of the 2 patients with PJK of pseudoarthrosis, and the other was lost follow-up. Revision surgery was performed in 1 of the patients with PJK of progressing thoracic kyphosis due to the natural history of AS. Conclusions： PJK could be presented in the characteristics of pseudoarthrosis, compression fracture and progressing thoracic kyphosis due to the natural history of AS. The age at initial surgery and types of osteotomy were the risk factors of PJK. The patients with lower preoperative PJA and SVA were found to have a higher risk of PJK.