Biomechanical comparison of different combinations of hook and screw in one spine motion unit - an experiment in porcine model

BMC Musculoskeletal Disorders

Po-Liang Lai²  Mu-Yi Liu¹  De-Mei Lee¹  Li-Huei Chen²  Ching-Lung Tai¹ 

[1] Graduate Institute of Medical Mechatronics, Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan;Department of Orthopaedic Surgery, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan

关键词: Porcine model;    Biomechanical study;    Lamina hook;    Pedicle screw;   

Others  :  1125583
DOI  :  10.1186/1471-2474-15-197

 received in 2013-10-29, accepted in 2014-05-30,  发布年份 2014

【 摘 要 】

Background

The biomechanical performance of the hooks and screws in spinal posterior instrumentation is not well-characterized. Screw-bone interface failure at the uppermost and lowermost vertebrae is not uncommon. Some have advocated for the use of supplement hooks to prevent screw loosening. However, studies describing methods for combined hook and screw systems that fully address the benefits of these systems are lacking. Thus, the choice of which implant to use in a given case is often based solely on a surgeon’s experience instead of on the biomechanical features and advantages of each device.

Methods

We conducted a biomechanical comparison of devices instrumented with different combinations of hooks and screws. Thirty-six fresh low thoracic porcine spines were assigned to three groups (12 per group) according to the configuration used for of fixation: (1) pedicle screw; (2) lamina hook and (3) combination of pedicle screw and lamina hook. Axial pullout tests backward on transverse plane in the direction normal to the rods were performed using a material testing machine and a specially designed grip with self-aligned function.

Results

The pullout force for the pedicle screws group was significantly greater than for the hooks and the combination (p < 0.05). However, no significant difference was found between the hooks and the combination (p > 0.05).

Conclusions

Pedicle screws achieve the maximal pullout strength for spinal posterior instrumentation.

【 授权许可】

   
2014 Tai et al.; licensee BioMed Central Ltd.

【 图 表 】

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