1. Biomechanical comparison of different combinations of hook and screw in one spine motion unit - an experiment in porcine model
- Author
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Ching-Lung Tai, Mu-Yi Liu, Po-Liang Lai, Li-Huei Chen, and De-Mei Lee
- Subjects
musculoskeletal diseases ,Lamina ,Hook ,Swine ,Bone Screws ,Sus scrofa ,In Vitro Techniques ,medicine.disease_cause ,Thoracic Vertebrae ,Biomechanical Phenomena ,Weight-bearing ,Weight-Bearing ,Motion ,Rheumatology ,Medicine ,Animals ,Orthopedics and Sports Medicine ,Pedicle screw ,Porcine model ,Fixation (histology) ,Lamina hook ,business.industry ,Anatomy ,equipment and supplies ,musculoskeletal system ,Biomechanical study ,Internal Fixators ,medicine.anatomical_structure ,surgical procedures, operative ,Thoracic vertebrae ,Equipment Failure ,Implant ,Stress, Mechanical ,business ,Research Article - Abstract
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). Conclusions Pedicle screws achieve the maximal pullout strength for spinal posterior instrumentation. more...
- Published
- 2014