Dick J C, Zdeblick T A, Bartel B D, Kunz D N
Orthopaedic Consultants, PA, Minneapolis, Minnesota, USA.
Spine (Phila Pa 1976). 1997 Feb 15;22(4):370-5. doi: 10.1097/00007632-199702150-00003.
This study was designed to evaluate the biomechanical performance of 5 different cross-link brands to determine which design characteristics are biomechanically desirable.
The Cotrel-Dubousset, Isola, Puno Winter Byrd, Rogozinski, and Texas Scottish Rite Hospital systems were assembled to vertebral models according to the manufacturer's specifications. Three constructs were tested for each brand of instrumentation: without cross-links, with one cross-link, and with two cross-links. Four modes of loading: axial, torsional, flexion-extension, and lateral-flexion were used. Load-displacement curves were plotted. The stiffness was calculated from the slope of these curves.
Five different rigid pedicle screw systems were tested to determine: 1) what are the characteristics of cross-link design that are most effective in limiting torsional motion; 2) whether two cross-links are more effective than one; and 3) whether cross-linkage increases the construct stiffness in lateral bending.
Cross-linkage has been shown to increase the torsional stiffness of rod and screw constructs. Increased construct stiffness has been correlated with higher fusion rates.
Increases in axial, flexion-extension, or lateral-flexion stiffness, with the addition of one or two cross-links, were not statistically significant. In torsional loading, increases in stiffness within brands were statistically significant in every case. The average increase was 44% with one added cross-link and 26% with two. The magnitude of the increase in torsional stiffness was compared with the cross-sectional area of the respective cross-link. Greater stiffness correlated with larger cross-sectional area (r = 0.81 for one cross-link, and r = 0.60 for two).
The use of cross-linkage in spinal fusion increases torsional stiffness in pedicle screw and hook constructs. This study 1) confirmed the effectiveness of cross-linkage in limiting torsional motion and showed the superiority of two cross-links to one cross-link in limiting torsional motion, 2) showed that increase of torsional stiffness of a cross-linked construct is proportional to the cross-sectional area of the cross-link, and 3) demonstrated that cross-links do not increases stiffness in the lateral flexion mode.
本研究旨在评估5种不同品牌横向连接装置的生物力学性能，以确定哪些设计特征在生物力学方面是理想的。
按照制造商的规格，将Cotrel-Dubousset、Isola、Puno Winter Byrd、Rogozinski和德克萨斯州苏格兰 rite医院系统组装到椎体模型上。每个品牌的器械测试三种结构：无横向连接、有一个横向连接和有两个横向连接。使用四种加载模式：轴向、扭转、屈伸和侧屈。绘制载荷-位移曲线。根据这些曲线的斜率计算刚度。
测试五种不同的刚性椎弓根螺钉系统，以确定：1）在限制扭转运动方面最有效的横向连接设计特征是什么；2）两个横向连接是否比一个更有效；3）横向连接是否会增加侧屈时结构的刚度。
横向连接已被证明可增加棒和螺钉结构的扭转刚度。结构刚度的增加与更高的融合率相关。
添加一个或两个横向连接后，轴向、屈伸或侧屈刚度的增加无统计学意义。在扭转载荷下，各品牌内刚度的增加在每种情况下均具有统计学意义。添加一个横向连接时平均增加44%，添加两个时增加26%。将扭转刚度增加的幅度与相应横向连接的横截面积进行比较。更大的刚度与更大的横截面积相关（一个横向连接时r = 0.81，两个横向连接时r = 0.60）。
在脊柱融合中使用横向连接可增加椎弓根螺钉和钩状结构的扭转刚度。本研究1）证实了横向连接在限制扭转运动方面的有效性，并显示了两个横向连接在限制扭转运动方面优于一个横向连接，2）表明横向连接结构的扭转刚度增加与横向连接的横截面积成正比，3）证明横向连接不会增加侧屈模式下的刚度。
