改良“Krag”置钉固定方式对胸腰段单椎体骨折复位程度的影响

The effect of modified "Krag" type of monosegmental transpedicular fixation on the reduction of single thoracolumbar fracture

目的:探讨U型椎弓根钉棒系统单节段改良"Krag"置钉固定方式对胸腰段单椎体骨折复位程度的影响。方法:对具备手术适应证的43例胸腰段单椎体骨折患者采用单节段经椎弓根改良"Krag"置钉固定结合椎间植骨融合治疗,术前、术后1周摄X线片,测量椎体成角、上下终板成角、椎体前缘高度与正常高度的比值,了解术前椎体压缩程度及术后骨折复位情况。把-5°≤上下终板成角≤5°视为骨折理想复位;上下终板成角<-5°为骨折过伸复位;上下终板成角>5°为骨折过屈复位。对于复位理想及不理想者,测量术前椎体压缩程度、矢状面螺钉角度(α,伤椎的矢状面螺钉角度;β,邻椎的矢状面螺钉角度)及连接棒预弯曲度(γ)等,并对两组测量结果进行对比分析。结果:术后37例(86%)骨折复位理想,6例(14%)骨折复位不够理想。两组术前椎体成角、上下终板成角及伤椎前缘高度与正常高度的比值无显著性差异(P>0.05),但术后1周差异有显著性(P<0.05)。矢状面螺钉角度(α、β)与连接棒预弯曲度(γ)的关系与骨折复位程度明显相关,-5°≤(α+β)-γ≤5°时骨折理想复位;α+β-γ<-5°时骨折过伸复位;α+β-γ>5°时骨折过屈复位。结论:改良"Krag"置钉固定方式中置入椎弓根螺钉椎体矢状面倾斜角度与连接棒预弯曲度的大小关系是决定骨折复位程度理想与否的关键。

Objective：To analyse the reduction effect of modified ＂Krag＂ type of monosegmental fixation by ＂U＂ type of transpedicular instrumentation on the treatment of single thoracolumbar fracture.Method：From February 2004 to April 2007,43 patients with appropriate indication were treated by the ＂Krag＂ type transpedicular monosegmental fixation and intervertebral bone grafting.Radiological outcomes were measured before operation and 7 days after operation,including the vertebral angle,the superior-inferior endplate angle and the ratio between anterior border height of fractured vertebrae and the height of normal vertebrae,in order to understand preoperative compression degree and postoperative reduction state of the fracture.If the superior-inferior endplate angle was ≥-5° and ≤5°,then fracture reduction was considered as ideal.Reduction was over extension if the superior-inferior endplate angle was 〈-5°,it was over flexion if the angle was 〉5°. To determine whether reduction was good or not,following data were studied,respectively,including the compression degree of the vertebrae and the way of transpedieular screw fixation,such as sagittal screw angle（α） in fractured vertebrae,sagittal screw angle（β） in adjacent vertebrae,and the prebending curvature of the rods （γ）.Rcsult：The ideal operative reduction was obtained in 37 patients （86%）,the redction was not ideal in 6 cases （14%）.There were no signifincant difference in the vertebral angle,the superior-inferior endplate angle and the ratio of anterior border height to the normal height before operation for both groups（P〉0.05）,however those showed signifincant difference at 7 days after operation（P〈0.05）.The value of α,β and γ was correlated to the fracture reduction.-5°≤（α＋β）-γ≤5° indicated an ideal reduction,α＋β-γ〈5° indicated reduction was over extension,and α＋β-γ〉5° meant the fracture compression was not corrected.Conclusion：The relationship of the inclined angle of the modified ＂Krag＂ type transpedicular screws in the saggital plane and the prebending curvature of the rods is the key point to determine.whether fracture reduction is good or not.