胸椎及胸腰椎后凸型休门病患者术后近端交界性后凸对比分析

Comparison of proximal junctional kyphosis after surgery between Scheuermann's patients with thoracic kyphosis versus thoracolumbar kyphosis

目的比较胸椎及胸腰椎后凸型休门病患者术后近端交界性后凸(proximal junctional kyphosis,PJK)的发生率,并探讨其相关危险因素。方法回顾性分析2006年4月至2014年7月,于我院接受后路内固定矫形融合手术治疗、术后随访2年以上的60例休门病后凸畸形患者,手术年龄为13~24岁,平均(17.6±4.1)岁。根据后凸顶椎位置不同,将患者分为胸椎组(顶椎位于T9及以上)和胸腰椎组(顶椎位于T10及以下),其中胸椎组25例,胸腰椎组35例。于站立位全脊柱X线片上测量全脊柱最大后凸Cobb’s角(global kyphosis,GK)、近端交界角(proximal junctional angle,PJA)、胸椎后凸角(thoracic kyphosis,TK)、腰椎前凸角(lumbar lordorsis,LL)、矢状面轴向垂直距离(sagittal vertical axis,SVA)和最上端固定椎(upper instrumented vertebra,UIV)-C7矢状面距离参数,对比两组间PJK发生率和矢状面形态的影像学参数。结果本研究平均随访(31.1±11.9)个月。胸椎组和胸腰椎组GK矫正率分别为(39.8±10.5)%和(48.6±14.4)%(P=0.012),末次随访时,后凸矫正丢失分别为(4.2±7.1)%和(9.3%±8.6)%(P=0.018)。术后随访中,19例发生了术后PJK,发生率为31.7%,最常见的原因为PJK I型(后方韧带破坏型)。其中胸腰椎组的PJK发生率显著高于胸椎组(42.9%vs.16.0%,P=0.027)。2例因进展性PJK接受支具治疗,1例因PJK伴顽固性背痛进行翻修手术。自术前至术后,胸腰椎组UIV-C7矢状面距离绝对值始终大于胸椎组。胸腰椎组的UIV位置和融合节段均显著低于胸椎组[T(6.0±1.9)vs.T(2.7±1.1),(10.2±1.8)vs.(12.4±0.9),P<0.001]。UIV使用钩的PJK发生率显著高于使用椎弓根螺钉患者(80%vs.27.3%,P<0.001),使用卫星棒者无一例发生PJK。结论休门病后凸畸形术后PJK的发生率为31.7%,主要发生于胸腰段后凸畸形患者。UIV位置低及使用钩、过大的后凸矫正率和UIV-C7矢状面距离等可能是胸腰椎后凸患者并发PJK的主要危险因素。

Objective To investigate the incidence and risk factors of proximal junctional kyphosis（ PJK） after posterior spinal instrumented correction and fusion between Scheuermann＇s patients with thoracic kyphosis versus thoracolumbar kyphosis. Methods Sixty patients with Scheuermann＇s kyphosis, whose mean age was（ 17.6 ± 4.1） years old（ range： 13- 24 years old） were recruited in this retrospective study. All the patients received posterior spinal instrumented correction and fusion from April 2006 to July 2014 in our hospital and were followed up for at least 2 years. The patients were divided into 2 groups according to the kyphosis apex level： the thoracic group（ apex at or above T9）（ n = 25） and the thoracolumbar group（ apex at or below T10）（ n = 35）. Radiographic measurements including global kyphosis（ GK）, proximal junctional angle（ PJA）, thoracic kyphosis（ TK）, lumbar lordorsis（ LL）, sagittal vertical axis（ SVA） and upper instrumented vertebra（ UIV）-C7 sagittal distance were performed on the standing upright lateral radiographs of the spine before and after surgery and at the latest follow-up. The incidenceof PJK and sagittal parameters were compared between the 2 groups. Results The average follow-up was（ 31.1 ± 11.9） months. While the correction rates of GK in the thoracic group and the thoracolumbar group were（ 39.8 ± 10.5） % and（ 48.6 ± 14.4） %（ P = 0.012）. The correction loss rates were（ 4.2 ± 7.1） % and（ 9.3 ± 8.6） %（ P = 0.018） at the latest follow up respectively. PJK occurred in 19 patients during the follow-up, thus the incidence was 31.7%. The most common type of PJK was posterior ligamentous failure（ type I）. The incidence of PJK in the thoracolumbar group was significantly higher than that in the thoracic group（ 42.9% vs. 16.0%, P = 0.027）. During the follow-up, 2 patients with progressive PJK received brace treatment and one with PJK underwent revision surgery for intractable back pain. UIV-C7 sagittal distance in the thoracolumbar group was significantly higher than that in the thoracic group from preoperatively to postoperatively. The thoracolumbar group had lower location of UIV and shorter fusion span than the thoracic group [ T（ 6.0 ± 1.9） vs. T（ 2.7 ± 1.1）,（ 10.2 ± 1.8） vs.（ 12.4 ± 0.9）, P〈0.001 ]. PJK tended to occur in the patients who were placed with hooks at UIV rather than pedicle screws（ 80% vs. 27.3%, P〈0.001）. No PJK was found in the patients who were added with satellite rods. Conclusions The incidence of PJK after posterior spinal instrumented correction and fusion in the patients with Scheuermann＇s kyphosis is approximately 31.7%. The patients with thoracolumbar kyphosis tend to have higher incidence of PJK. Lower location of UIV and internal fixation material, over-correction of GK and larger UIV-C7 sagittal distance may be the main risk factors for PJK.