Effects of neck movements on stability and subsidence in cervical interbody fusion: an in vitro study
Effects of neck movements on stability and subsidence in cervical interbody fusion: an in vitro study
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DOI：
10.3171/spi.2001.94.1.0097
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发表时间：
2001-01-01
影响因子：
4.1
通讯作者：
Claes, L
中科院分区：
文献类型：
--
作者：
Kettler, A;Wilke, HJ;Claes, L
对象。本体外研究的目的是确定模拟术后颈部运动对四种不同的颈椎前路椎间融合装置的稳定效果和沉降的影响。重点讨论了沉陷与脊柱稳定性的关系。在50 N轴向预载荷的标准柔韧性试验中，对24例人颈椎标本进行了WING、BAK/C、AcroMed I/F笼或骨水泥稳定前后的柔韧性测试。随后，在随机方向上施加700个纯矩加载循环（+/- 2 Nm）来模拟生理颈部运动。在50、100、200、300、500和700次加载循环后，进行了额外的柔韧性测试，并测量了沉降深度。在所有四组中，模拟术后颈部运动导致活动范围（ROM）增加0.4至3.1度，中性区增加0.1至4.2度。这种灵活性的增加在伸展中最为明显，其次是屈曲、侧屈和轴向旋转。循环加载后，安装AcroMed笼组（右侧弯曲3.3度，左侧轴向旋转3.5度，屈曲7.8度，伸展8.3度）和骨水泥组（分别为5.4度，2.5度，7.4度和8.8度）的ROM均低于对照组；使用WING（分别为6.3度、5.4度、9.7度和6.9度）和BAK笼（分别为6.2度、4.5度、10.2度和11.6度）。模拟重复的颈部运动不仅会增加灵活性，还会使植入物下沉到邻近的椎骨。灵活性增加和下沉之间的关系似乎取决于植入物的设计：下沉的BAK/C笼部分支持稳定性，而下沉的WING笼和AcroMed笼则没有。
Object. The aim of this in vitro study was to determine the influence of simulated postoperative neck movements on the stabilizing effect and subsidence of four different anterior cervical interbody fusion devices. Emphasis was placed on the relation between subsidence and spinal stability.Methods. The flexibility of 24 human cervical spine specimens was tested before and directly after being stabilized with a WING, BAK/C, AcroMed I/F cage, or with bone cement in standard flexibility tests under 50 N axial preload. Thereafter, 700 pure moment loading cycles (+/- 2 Nm) were applied in randomized directions to simulate physiological neck movements. Additional flexibility tests in combination with measurements of the subsidence depth were conducted after 50, 100, 200, 300, 500, and 700 loading cycles.In all four groups, simulated postoperative neck movements caused an increase of the range of motion (ROM) ranging from 0.4 to 3.1 degrees and of the neutral zone from 0.1 to 4.2 degrees. This increase in flexibility was most distinct in extension followed by flexion, lateral bending, and axial rotation. After cyclic loading, ROM tended to be lower in the group fitted with AcroMed cages (3.3 degrees in right lateral bending, 3.5 degrees in left axial rotation, 7.8 degrees in flexion, 8.3 degrees in extension) and in the group in which bone cement was applied (5.4 degrees, 2.5 degrees, 7.4 degrees, and 8.8 degrees, respectively) than in those fu;ed with the WING (6.3 degrees, 5.4 degrees, 9.7 degrees, and 6.9 degrees, respectively) and BAK cages (6.2 degrees, 4.5 degrees, 10.2 degrees, and 11.6 degrees, respectively).Conclusions. Simulated repeated neck movements not only caused an increase of the flexibility but also subsidence of the implants into the adjacent vertebrae. The relation between flexibility increase and subsidence seemed to depend on the implant design: subsiding BAK/C cages partially supported stability whereas subsiding WING cages and AcroMed cages did not.