Biomechanical characteristics of axial controlled dynamic intramedullary nail

Abstract

AIM：Interlocking intramedullary nail is commonly used in the internal fixation of fractures of long tubular bones. Its static feature may induce the mechanical failure of materials, and result in complications. This article describes the design and explores the biomechanical properties of axial controlled dynamic intramedullary nail.

METHODS: Experiments were conducted in the Biomechanical Laboratory of Southern Medical University from October to December 2006. ①Self-made axial controlled dynamic intramedullary nail was composed of a lock nail and a intramedullary nail. Two axial controlled panels with 60° angle were added at the proximal end of the intramedullary nail. The obverse side of the axial controlled panels was ladder-shaped, with the oblique angle of 10°, 0.8 mm in thick, 8 mm in height. ②Eight pair specimens of adult tibias were made into A1 type fracture models according to OTA with a wire saw. Axial controlled dynamic intramedullary nail and Grosse & Kempf nail were implanted into the tibias in MTS858 machine. Torsional, bending and axial compressive tests were made on the specimens. The axial and bending loading was 700 N and 300 N, respectively, and the test velocity was 0.1 mm/s; the torsional moment was 4 Nm and the test velocity was 0.3 (°)/s.

RESULTS: Axial controlled dynamic intramedullary nail produced a significantly lower strain than the Grosse & Kempf nail (P < 0.01). There was no significant difference in torsional stiffness, and bending stiffness of coronal and sagittal plane between the axial controlled dynamic intramedullary nail and the Grosse & Kempf nail (P > 0.05).

CONCLUSION: The axial controlled dynamic intramedullary nail has the similar torsional and bending stiffness comparable with the Grosse & Kempf nail, and the biomechanical properties of axial controlled dynamic intramedullary nail in resistance to compression are significantly better than that of Grosse & Kempf nail. Axial controlled dynamic intramedullary nail is an effective and convenient implant to treat tibial fracture.

Wang J, Peng XS, Wang GD, Pan T.Biomechanical characteristics of the axial controlled dynamic intramedullary nail. Zhongguo Zuzhi Gongcheng Yanjiu yu Linchuang Kangfu 2008;12(4):623-626(China)
[www.zglckf.com/zglckf/ejournal/upfiles/08-4/4k-623(ps).pdf]

摘要
目的：交锁髓内钉是目前国内外应用于长管状骨骨折内固定的主流，但其静力性固定特性将有可能导致材料的力学失败，引起相关并发症，基于此，设计了轴向控制动力性锁钉并进行生物力学测试。
方法：实验于2006-10/12在南方医科大学生物力学实验室完成。①自制轴向控制动力性锁钉的结构：由锁钉和髓内钉组成，髓内钉的近端增加了2个夹角为60°轴向控制板，轴向控制板正面为梯形，斜角为10°，厚0.8 mm，高度为8 mm。②轴向控制动力性锁钉与交锁钉生物力学比较：将8对新鲜尸胫骨标本用线锯在胫骨中段制成OTA分类A1型骨折模型，分别用胫骨轴向控制动力性锁钉与交锁钉固定，安装在MTS858实验机上，进行抗压缩、弯曲及扭转测试分析，施加的轴向负荷为700 N，测试速度0.1 mm/s；弯曲负荷为300 N，速度0.1 mm/s，扭矩4 Nm，速度0.3 （°）/s。
结果：轴向控制动力性锁钉压缩应变值明显小于交锁钉组，差异有非常显著性意义（P < 0.01），轴向控制动力性锁钉抗的扭转刚度、冠状面和矢状面弯曲刚度与交锁钉组比较差异无统计学意义（P > 0.05）。
结论：轴向控制动力性锁钉在抗弯曲和抗扭转方面能达到或接近交锁钉的强度，在抗压缩方面强于交锁钉。说明轴向控制动力性锁钉能起到动力性固定的作用，具有良好的生物力学性能，是治疗胫骨骨折的一种可供选择的新型髓内固定器械，能够满足临床需要。
关键词：胫骨；骨折；内固定；生物力学

王军，彭新生，王国栋，潘滔．轴向控制动力性锁钉的生物力学特性[J].中国组织工程研究与临床康复，2008，12(4):623-626
[www.zglckf.com/zglckf/ejournal/upfiles/08-4/4k-623(ps).pdf]