背景:颈前路椎间盘切除融合术(ACDF)后融合失败可能会导致症状性假性关节病。传统诊断涉及计算机断层扫描以检测桥接骨和/或屈伸X射线照片,以评估节段运动是否高于特定阈值;但是,目前没有经过充分验证的诊断测试.我们提出了一种生物力学上合理的方法来实现假关节炎的可靠诊断测试。
目的:开发并测试一种基于生物力学的假关节病诊断方法。
方法:文献综述,理论的发展,对以前发表的以手术探查为黄金标准的研究进行重新分析,并对汇总研究进行回顾性分析,以了解融合时间。
方法:使用全自动方法测量椎间盘空间应变(椎间盘空间高度的变化除以初始高度)。测量误差与报告的小梁骨失效应变相结合,导致了拟议的应变阈值,用于诊断ACDF后的假关节炎。我们重新分析了先前报道的无症状志愿者的屈伸X光片,以评估屈伸X光片是否,在没有融合手术的情况下,可以预期在运动段上提供足够的应力,以允许可靠的基于应变的融合评估。通过重新分析先前报道的ACDF后屈伸X光片,评估了基于应变和旋转的假关节炎诊断的敏感性和特异性。术中融合评估也可用。最后,我们使用1,369例患者在ACDF手术后6周至84个月获得的9,869例屈伸X线片评估了应变随时间的变化.
结果:从射线照片自动测量椎间盘间隙应变的估计误差约为3%,报告的桥接骨的失效应变小于2.5%。在这个基础上,我们提出了一个5%的应变阈值诊断假关节炎。对术中融合评估可用的研究的重新分析显示,基于应变的假关节病诊断的敏感性为67%,特异性为82%。这与基于轮换的诊断相当。对ACDF后屈伸X光片的分析显示,应变快速减少长达24个月,其次是持续84个月的缓慢下降。当旋转小于2度时,在约14%的病例中,基于应变的诊断与基于旋转的诊断不同.
结论:我们提出了基于骨失效应变的假关节标准化诊断的步骤,测量误差,和回顾性数据。这些步骤包括获得高质量的屈伸研究,建议的诊断阈值的应用,以及使用图像稳定进行结论性诊断,当运动接近阈值时。以最小的辐射暴露进行准确诊断的必要性强调了在ACDF手术后诊断假关节炎时需要进一步优化和标准化。
结论:在有症状的脊柱融合后患者中,诊断或排除假性关节炎很重要。目前没有针对这种情况的经过充分验证的诊断测试。将基于应变的椎间运动分析纳入诊断中可能会导致用于检测脊柱假关节病的标准化且经过验证的测试。
BACKGROUND: Failure to fuse following anterior cervical discectomy and fusion (ACDF) may result in symptomatic
pseudoarthrosis. Traditional diagnosis involves computerized tomography to detect bridging bone and/or flexion-extension radiographs to assess whether segmental motion is above specific thresholds; however, there are currently no well-validated diagnostic tests. We propose a biomechanically rational approach to achieve a reliable diagnostic test for
pseudoarthrosis.
OBJECTIVE: Develop and test a biomechanically based approach to the diagnosis of
pseudoarthrosis.
METHODS: Literature review, development of theory, re-analysis of a previously published study with surgical exploration as the gold-standard, and retrospective analysis of pooled studies to understand time to fusion.
METHODS: Fully automated methods were used to measure disc space strains (change in disc space height divided by initial height). Measurement error combined with the reported failure strain of trabecular bone led to a proposed strain threshold for diagnosis of pseudoarthrosis following ACDF. We reanalyzed previously reported flexion-extension radiographs for asymptomatic volunteers to assess whether flexion-extension radiographs, in the absence of fusion surgery, can be expected to provide sufficient stress on motion segments to allow for reliable strain-based fusion assessment. The sensitivity and specificity of strain- and rotation-based
pseudoarthrosis diagnosis were assessed by reanalysis of previously reported post-ACDF flexion-extension radiographs, where intraoperative fusion assessments were also available. Finally, we assessed changes in strain over time using 9,869 flexion-extension radiographs obtained 6 weeks to 84 months post-ACDF surgery from 1,369 patients.
RESULTS: The estimated error in automated measurement of disc space strain from radiographs was approximately 3%, and the reported failure strain of bridging bone was less than 2.5%. On that basis, we propose a 5% strain threshold for
pseudoarthrosis diagnosis. Reanalysis of a study in which intraoperative fusion assessments were available revealed 67% sensitivity and 82% specificity for strain-based diagnosis of pseudoarthrosis, which was comparable to rotation-based diagnosis. Analysis of post-ACDF flexion-extension radiographs revealed rapid strain reduction for up to 24 months, followed by a slower decrease for up to 84 months. When rotation is less than 2 degrees, the strain-based diagnosis differed from the rotation-based diagnosis in approximately 14% of the cases.
CONCLUSIONS: We propose steps for standardizing diagnosis of pseudoarthrosis based on the failure strain of bone, measurement error, and retrospective data. These steps include obtaining high-quality flexion-extension studies, the application of proposed diagnostic thresholds, and the use of image stabilization for conclusive diagnosis, when motion is near thresholds. The necessity for an accurate diagnosis with minimal radiation exposure underscores the need for further optimization and standardization in diagnosing pseudoarthrosis following ACDF surgery.
CONCLUSIONS: In a symptomatic post-spine fusion patient, it is important to diagnose or rule-out pseudoarthrosis. There are currently no well-validated diagnostic tests for this condition. Incorporating strain-based intervertebral motion analysis into the diagnosis could lead to a standardized and validated test for detecting spine pseudoarthrosis.