Purpose

The authors recently proposed the novel radiologic assessment method to measure chronological screw position changes precisely. The aim of this study was to predict the late occurrence of screw loosening, which was diagnosed by the radiographic lucent zone, by evaluating screw position changes at an early postoperative stage using the novel method.

Methods

Forty-three patients who underwent thoracolumbar screw fixation and follow-up computed tomography (CT) scans on the day, between 1 and 5 weeks, and at more than 6 months after surgery were retrospectively evaluated. Screw images were generated from CT data. Screw position changes were evaluated by superposing screw images on the day and between 1 and 5 weeks after surgery. Screw loosening was diagnosed by the radiographic lucent zone on CT images at 6 months or later post-surgery, and patients were classified into screw loosening and non-loosening groups. The early screw position changes were compared between the two groups.

Results

Significant differences in early screw position changes were found between the screw loosening and non-loosening groups in Mann–Whitney U test (p = 0.001). On the receiver operating characteristic (ROC) curve analysis, the area under the ROC curve was 0.791, and the best cutoff value of early screw position change for the prediction of screw loosening was 0.83 mm with a sensitivity of 64.0% and a specificity of 88.9%.

Conclusion

We calculated a cutoff value of the screw position changes at an early postoperative stage for the prediction of subsequent development of screw loosening with the radiographic lucent zone.

中文翻译：

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术后早期，在随后发生螺丝松动之前，螺丝位置发生变化。

目的

作者最近提出了一种新颖的放射学评估方法，可以精确地测量螺丝的时间顺序。这项研究的目的是通过使用新方法评估术后早期螺丝位置的变化，从而预测由放射线透亮区诊断出的螺丝松动的晚期发生。

方法

回顾性分析了当天，术后1至5周以及术后6个月以上接受胸腰椎螺钉固定和后续计算机断层扫描（CT）扫描的43例患者。螺钉图像是从CT数据生成的。通过在手术当天和手术后1至5周内叠加螺丝图像来评估螺丝位置的变化。术后6个月或更晚，通过CT图像上的射线透亮区诊断出螺钉松动，并将患者分为螺钉松动和非松动组。比较两组的早期螺钉位置变化。

结果

在Mann–Whitney U检验中，发现松动组和非松动组之间早期螺钉位置变化存在显着差异（p  = 0.001）。在接收器工作特性（ROC）曲线分析中，ROC曲线下的面积为0.791，并且预测螺钉松动的早期螺钉位置变化的最佳截止值为0.83 mm，灵敏度为64.0％，特异性为88.9。 ％。

结论

我们计算了术后早期早期螺钉位置变化的临界值，以预测放射线透亮区随后螺钉松弛的发展。