CT冠状位重建图像和传统方法判定脊柱内固定螺钉松动的敏感度和特异性

Sensitivity and specificity of coronal computed tomography reconstruction and traditional methods for determining screw loosening in spinal internal fixation

背景:椎弓根螺钉松动是脊柱内固定后的严重并发症,既往对螺钉松动的报道还是依赖CT轴位像进行判断。目的:对比研究CT冠状位重建图像及X射线片和轴位CT图像的传统方法在判定脊柱内固定螺钉松动的敏感度和特异性。方法:收集了23例在河南省人民医院行脊柱术后内固定翻修的病例,其中短节段固定14例,长节段固定患者9例,退变性疾病患者17例,骨折患者6例。术前采用CT冠状位重建图像以及传统X射线片和轴位CT图像两种方法进行椎弓根螺钉松动判定。2名医生独立阅片互不干扰,术前评估所有内固定装置是否存在松动。术中共探查螺钉171枚,术中采用数字化扭力计进行探查,依据扭力判定螺钉是否存在松动情况,分别统计两种方法的敏感度和特异性。该临床研究的实施符合《赫尔辛基宣言》和河南省人民医院的相关伦理要求,患者对治疗知情同意,并签署知情同意书。结果与结论:①术中共探查171枚螺钉,其中69枚螺钉出现了松动,螺钉松动比率为40.1%;其中松动螺钉的扭力为(13.9±17.2)Ncm,未松动螺钉的扭力为(154.9±72.3)Ncm;②采用冠状位重建法进行判定的敏感度为76.2%,特异性为89.8%,准确度为80.1%;采用传统方法的敏感度为63.7%,特异性为79.3%,准确度为69.0%,两种方法对比,冠状位重建法的敏感度、特异性以及准确度均高于传统方法(P<0.05);③两种判定方法的观察者组内相关系数(ICC)均大于0.75,表明两种判定方法的一致性良好;④结果说明,CT冠状位重建图像简便易行,可以提高脊柱内固定术后螺钉松动判定的准确性。

BACKGROUND:Pedicle screw loosening is a serious complication of spinal internal fixation,and previous reports on the determination of screw loosening still focused on computed tomography(CT)axial images.OBJECTIVE:To compare the sensitivity and specificity of coronal CT reconstruction using traditional methods,including X-ray and axial CT images,in determining screw loosening.METHODS:This study enrolled a total of 23 patients who underwent spinal revision surgery in Henan Provincial People’s Hospital,including 17 patients with degenerative diseases and 6 patients with fractures.There were 14 patients with short segmental fixation and 9 patients with long segmental fixation.Coronal CT reconstruction and traditional X-ray and axial CT images were used to determine pedicle screw loosening preoperatively.Two doctors read the film independently without interfering with each other.Preoperative assessment was made for loosening of all fixation devices.A total of 171 screws were detected intraoperatively by digital torsion meter,and whether the screws were loose was determined according to the torsion.The sensitivity and specificity of the two methods were calculated separately.The clinical study was carried out in accordance with the Helsinki Declaration and the relevant ethical requirements of Henan Provincial People’s Hospital.Patients were informed of the treatment and signed an informed consent form.RESULTS AND CONCLUSION:A total of 171 screws were examined,of which 69 screws were loose,and the loosening rate was 40.1%.The torsion force was(13.9±17.2)Ncm for loose screws and(154.9±72.3)Ncm for unloosened screws.The sensitivity,specificity,and accuracy of coronal CT reconstruction were 76.2%,89.8%,and 80.1%,respectively.The sensitivity,specificity,and accuracy of the traditional method were 63.7%,79.3%,and 69.0%,respectively.The sensitivity,specificity,and accuracy of the coronal CT reconstruction were higher than those of the traditional method(P<0.05).The intra-observer correlation coefficients of the two methods were both greater than 0.75,indicating a good consistency between the two methods.To conclude,coronal CT reconstruction is simple and convenient,which can improve the accuracy of screw loosening determination after spinal internal fixation.