In Vivo Evidence of Early Instability and Late Stabilization in Motion Segments Immediately Superior to Anterior Cervical Arthrodesis.
In Vivo Evidence of Early Instability and Late Stabilization in Motion Segments Immediately Superior to Anterior Cervical Arthrodesis.
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前瞻性队列研究。通过双平面X线片测量，确定影响颈椎前路椎间盘切除融合术（ACDF）后相邻节段运动学的患者因素。相邻节段疾病（ASD）的病因可能是多因素的。以前的研究已经调查了患者因素和ASD之间的关联，尽管很少有人试图将患者因素与可能解释ASD发展的脊柱机械变化联系起来。先前的研究通过静态屈曲/伸展X线片手动测量椎间运动，然而，手动测量不可靠，并且这些研究未能测量旋转期间的椎间运动。术前和ACDF后1年，患者在动态双平面X线摄影系统中以每秒30张图像的速度拍摄了连续的颈椎屈曲/伸展和轴向旋转运动。使用经验证的跟踪过程，将受试者特定CT扫描生成的数字重建X线片与双平面X线片进行匹配。动态运动学和术前椎间盘高度计算从这个跟踪过程。术前MRI评估椎间盘膨出。收集患者年龄、性别、BMI、吸烟状况、糖尿病、精神病史、是否存在诱发事件和症状持续时间。进行多变量线性回归，以确定与术后1年相邻节段运动学变化相关的患者因素。63例患者完成了术前和术后测试。上级相邻节段椎间盘高度和椎间盘膨出预测术后上级相邻节段ROM的变化。下相邻节段椎间盘膨出、吸烟史和使用精神病药物可预测术后下相邻节段屈曲/伸展ROM的变化。预先存在的相邻节段椎间盘退变，如椎间盘高度和椎间盘膨出所示，与ACDF后相邻节段活动减少相关，而预先存在的相邻椎间盘退变缺失与ACDF后相邻节段活动增加相关。这些发现提供了体内证据，支持椎间盘退变的病理生理学早期不稳定和晚期稳定。
Prospective cohort study. To identify patient factors that affect adjacent segment kinematics after anterior cervical discectomy and fusion (ACDF) as measured by biplane radiography. The etiology of adjacent segment disease (ASD) may be multifactorial. Previous studies have investigated associations between patient factors and ASD, although few attempted to link patient factors with mechanical changes in the spine that may explain ASD development. Previous studies manually measured intervertebral motion from static flexion/extension radiographs, however, manual measurements are unreliable, and those studies failed to measure intervertebral motion during rotation. Patients had continuous cervical spine flexion/extension and axial rotation movements captured at 30 images per second in a dynamic biplane radiography system preoperatively and 1 year after ACDF. Digitally reconstructed radiographs generated from subject-specific CT scans were matched to the biplane radiographs using a validated tracking process. Dynamic kinematics and preoperative disc height were calculated from this tracking process. Preoperative MRIs were evaluated for disc bulge. Patient age, sex, BMI, smoking status, diabetes, psychiatric history, presence of an inciting event, and length of symptoms were collected. Multivariate linear regression was performed to identify patient factors associated with 1-year postoperative changes in adjacent segment kinematics. Sixty-three patients completed preoperative and postoperative testing. Superior adjacent segment disc height and disc bulge predicted the change in superior adjacent segment ROM after surgery. Inferior adjacent segment disc bulge, smoking history, and the use of psychiatric medications predicted the change in inferior adjacent segment flexion/extension ROM after surgery. Preexisting adjacent segment disc degeneration, as indicated by disc height and disc bulge, was associated with reduced adjacent segment motion after ACDF, while lack of preexisting adjacent disc degeneration was associated with increased adjacent segment motion after ACDF. These findings provide in vivo evidence supporting early instability and late stabilization in the pathophysiology of disc degeneration.