Palmer Daniel Kyle, Rios David, Patacxil Wyzscx Merfil, Williams Paul A, Cheng Wayne K, İnceoğlu Serkan
Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, Loma Linda University, Loma Linda, CA.
Int J Spine Surg. 2012 Dec 1;6:8-12. doi: 10.1016/j.ijsp.2011.12.002. eCollection 2012.
Screw length pertains to stability in various orthopedic fixation devices. There is little or no information on the relationship between plate pullout strength and screw length in anterior lumbar interbody fusion (ALIF) plate constructs in the literature. Such a description may prove useful, especially in the treatment of osteoporotic patients where maximizing construct stability is of utmost importance. Our purpose is to describe the influence of screw length on ALIF plate stability in severely and mildly osteoporotic bone foam models.
Testing was performed on polyurethane foam blocks with densities of 0.08 g/cm(3) and 0.16 g/cm(3). Four-screw, single-level ALIF plate constructs were secured to the polyurethane foam blocks by use of sets of self-tapping cancellous bone screws that were 20, 24, 28, 32, and 36 mm in length and 6.0 mm in diameter. Plates were pulled out at 1 mm/min to failure, as defined by consistently decreasing load despite increasing displacement.
Pullout loads in 0.08-g/cm(3) foam for 20-, 24-, 28-, 32-, and 36-mm screws averaged 303, 388, 479, 586, and 708 N, respectively, increasing at a mean of 25.2 N/mm. In 0.16-g/cm(3) foam, pullout loads for 20-, 24-, 28-, 32-, and 36-mm screws averaged 1004, 1335, 1569, 1907, and 2162 N, respectively, increasing at a mean of 72.2 N/mm.
The use of longer screws in ALIF plate installation is expected to increase construct stability. Stabilization from screw length in osteoporotic patients, however, is limited.
螺钉长度与各种骨科固定装置的稳定性相关。在文献中，关于腰椎前路椎间融合（ALIF）钢板结构中钢板拔出强度与螺钉长度之间的关系，几乎没有或根本没有相关信息。这样的描述可能会被证明是有用的，特别是在治疗骨质疏松患者时，最大化结构稳定性至关重要。我们的目的是描述在严重和轻度骨质疏松骨泡沫模型中，螺钉长度对ALIF钢板稳定性的影响。
对密度分别为0.08 g/cm³和0.16 g/cm³的聚氨酯泡沫块进行测试。使用长度分别为20、24、28、32和36 mm、直径为6.0 mm的自攻松质骨螺钉将四级单节段ALIF钢板结构固定到聚氨酯泡沫块上。以1 mm/min的速度拔出钢板直至失效，失效定义为尽管位移增加但载荷持续下降。
在0.08 g/cm³的泡沫中，20、24、28、32和36 mm螺钉的拔出载荷平均分别为303、388、479、586和708 N，平均每毫米增加25.2 N。在0.16 g/cm³的泡沫中，20、24、28、32和36 mm螺钉的拔出载荷平均分别为1004、1335、1569、1907和2162 N，平均每毫米增加72.2 N。
在ALIF钢板安装中使用更长的螺钉有望增加结构稳定性。然而，骨质疏松患者中螺钉长度带来的稳定性增强是有限的。
