Biomechanical testing of a unique built-in expandable anterior spinal internal fixation system

BMC Musculoskeletal Disorders

Hai Lv¹  Zhong Chen¹  Yu Zhang²  Yan-Fang Xu³  Chu-Song Zhou¹ 

[1] Department of Orthopaedics, Zhujiang Hospital of Southern Medical University (First Military Medical University), Guangzhou 510282, People’s Republic of China;Department of Orthopaedics, Guangzhou General Hospital of Guangzhou Military Command, Guangzhou 510010, China;Department of Orthopaedics, The Second People’s Hospital of Changzhi City, No 83 Speace West Street, Changzhi City, Shanxi 046000, People’s Republic of China

关键词: Pullout strength;    Biomechanical;    Internal fixation;    Expansion screw;    Anterior fixation;    Thoracolumbar;   

Others  :  1090763
DOI  :  10.1186/1471-2474-15-424

 received in 2014-05-08, accepted in 2014-12-05,  发布年份 2014

【 摘 要 】

Background

Expandable screws have greater pullout strength than conventional screws. The purpose of this study was to compare the biomechanical stability provided by a new built-in expandable anterior spinal fixation system with that of 2 commonly used anterior fixation systems, the Z-Plate and the Kaneda, in a porcine partial vertebral corpectomy model.

Methods

Eighteen porcine thoracolumbar spine specimens were randomly divided into 3 groups of 6 each. A vertebral wedge osteotomy was performed by removing the anterior 2/3 of the L1 vertebral body and the T15/L1 disc. Vertebrae were fixed with the Z-Plate, Kaneda, or expandable fixation system. The 3-dimensional spinal range of motion (ROM) of specimens in the intact state (prior to osteotomy), injured state (after osteotomy), and after internal fixation were recorded. The pullout strength and maximum torque of common anterior screws, the expandable anterior fixation screw unexpanded, and the expandable anterior fixation screw expanded was tested.

Results

After internal fixation, the expandable device and Z-plate system exhibited higher left bending motion than the Kaneda system (5.50° and 5.37° vs. 5.04, p = 0.001 and 0.008, respectively), and the Z-plate and Kaneda groups had significantly higher left axial and right axial rotation ROM as compared to the expandable device group (left axial rotation: 5.23° and 5.02° vs. 4.53°; right axial rotation: 5.23° and 5.08° vs. 4.49°). The maximum insertion torque of the expandable device was significantly greater than of a common screw (5.10 vs. 3.75 Ns). The maximum pullout force of the expandable device expanded was significantly higher than that of the common screw and the expandable device unexpanded (3,035.48 N vs. 1,827.38 N and 2,333.49 N).

Conclusions

The built-in anterior fixation system provides better axial rotational stability as compared to the other 2 systems, and greater maximum torque and pullout strength than a common fixation screw.

【 授权许可】

   
2014 Zhou et al.; licensee BioMed Central Ltd.

【 图 表 】

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