Department of Orthopaedics, University Hospital of Valladolid, Calle Ramon y Cajal, Valladolid, Spain.
Department of Orthopaedics, Scripps Clinic, N Torrey Pines Rd, La Jolla, CA, USA.
Spine J. 2024 Jan;24(1):125-131. doi: 10.1016/j.spinee.2023.09.008. Epub 2023 Sep 17.
Proper alignment and tightening of the pedicle screw/rod assembly after instrumented posterior fusion of the lower spine is known to be crucial in order to achieve satisfactory clinical results. Such interfacing angle mismatches indicate stress overloading of the implant system.
The objective of this study is to investigate the incidence of postoperative screw/rod interfacing angle mismatch and to analyze the impact of mismatches on clinical outcome in terms of (1) revision surgery, (2) adjacent segment degeneration (ASD), and (3) pain.
This is a monocentric retrospective observational study.
Patients underwent fusion surgery with pedicle screw/rod systems for predominantly degenerative pathologies.
Pedicle screw/rod interfacing angle mismatch (mismatch is the angular deviation from 90° formed by the rod axis and the pedicle screw head axis as an indicator for missing form-fit) revision rate, ASD at the immediately adjacent cranial segment and VAS pain.
Revision refers to subsequent procedures in which all or part of the original implant configuration is changed or removed. Radiographic parameters are evaluated using a/p and lateral radiographs at final follow-up. The interfacing angle mismatch between pedicle screw and rod is measured as the angle between two parallel lines on either side of each pedicle screw head and a line laterally along the associated rod. Multiple comparisons are counteracted by Bonferroni correction, adjusted significance level is at *p<.01.
Pedicle screw and rod interfacing angle mismatch was found in 171/406 (42.1%) of patients undergoing fusion surgery, affecting 613/3016 (20.3%) screws. The overall revision incidence was 11.8% (48/406), and a new ASD occurred in 12.1% of all patients (49/406) with an average follow-up of 5 years. Mean VAS pain score at final follow-up was 2.0. Comparison of the two groups with and without mismatches revealed statistically significantly higher (1) numbers of revision procedures performed (26.9% vs 0.9%), (2) numbers of new ASD developed (27.5% vs 3.8%), and (3) higher VAS pain scores (2.8/10 vs 1.4/10) for cases with mismatch. When comparing patients who underwent intraoperative correction and/or reduction with those who did not, statistically significant more screw mismatches (63.4% vs 39.7%) and revision surgeries (29.3% vs 9.9%) were noted in patients who had these forceful maneuvers.
Pedicle screw/rod interfacing angle mismatch is a frequent occurrence after fusion surgery. Mismatches indicate that the construct was assembled under mechanical stress. All preventable mechanical stresses, for example, unintentional uncontrolled forces on the instrumentation, should be avoided as much as possible, as they can negatively influence the clinical outcome.
众所周知，为了获得满意的临床结果，在下脊柱后路融合术后，正确调整和拧紧椎弓根螺钉/棒组件至关重要。这种界面角度不匹配表明植入物系统承受过载。
本研究旨在调查术后螺钉/棒界面角度不匹配的发生率，并分析不匹配对临床结果的影响，包括（1）翻修手术，（2）相邻节段退变（ASD）和（3）疼痛。
这是一项单中心回顾性观察研究。
患者接受了主要因退行性病变而行的椎弓根螺钉/棒系统融合手术。
椎弓根螺钉/棒界面角度不匹配（不匹配是指杆轴和椎弓根螺钉头轴形成的 90°角度的偏差，作为缺失形式适配的指示）的翻修率、紧邻颅侧节段的 ASD 和 VAS 疼痛。
翻修是指对原始植入物配置的全部或部分进行更改或去除的后续程序。使用最终随访时的前后位和侧位 X 线片评估影像学参数。通过在每个椎弓根螺钉头的两侧画两条平行线，并沿相关杆画一条平行线，测量椎弓根螺钉和杆之间的界面角度不匹配。通过 Bonferroni 校正来抵消多次比较，调整后的显著性水平为*p<.01。
在接受融合手术的 406 名患者中的 171 名（42.1%）中发现了椎弓根螺钉和杆的界面角度不匹配，影响了 3016 个螺钉中的 613 个（20.3%）。总体翻修发生率为 11.8%（48/406），所有患者中有 12.1%（49/406）出现新的 ASD，平均随访时间为 5 年。最终随访时的平均 VAS 疼痛评分为 2.0。比较有和没有不匹配的两组，发现（1）进行的翻修手术数量统计学显著更高（26.9% vs 0.9%），（2）发生新的 ASD 数量统计学显著更高（27.5% vs 3.8%），以及（3）疼痛评分更高（2.8/10 vs 1.4/10）。在比较进行术中矫正和/或复位的患者与未进行的患者时，在进行这些强制性操作的患者中，螺钉不匹配（63.4% vs 39.7%）和翻修手术（29.3% vs 9.9%）的数量统计学显著更高。
椎弓根螺钉/棒界面角度不匹配在融合手术后经常发生。不匹配表明构建是在机械应力下组装的。应尽可能避免所有可预防的机械应力，例如对器械的无意识、不受控制的力，因为它们会对临床结果产生负面影响。
