Biomechanical effects of vertebroplasty on thoracolumbar burst fracture with transpedicular fixation: a finite element model analysis.
OBJECTIVE
To investigate the biomechanical effects of augmentation of the fractured vertebrae after posterior instrumentation.


METHODS
By simulating internal fixation plus augmentation with cement, eight tridimensional, anatomically detailed finite element models of the T11-L1 functional spinal junction were developed. Two kinds of models for mimicking different severity of the fracture were established according to the Denis' classification. Augmentation with cement was conducted after reduction with posterior fixation using a universal spine system. These models assumed a three-column loading configuration as follows: compression, anteflexion, extension, lateroflexion and axial rotation. Stress of the implants and spine was evaluated.


RESULTS
Data showed that for severely fractured models, augmentation apparently decreased the von Mises stresses by 50% for the rods and 40% for the screws, about 40% for the inferior endplate of T11, and 50% for the superior endplate of L1 in vertical compression and other load situations.


CONCLUSIONS
We should only apply vertebroplasty to prevent correction loss and implants failure based on the fact that it could significantly decrease stress of the instrumentations and spine when the vertebrae are severely fractured.


METHODS
Level IV, biomechanical study.
Biomechanics Labs of Orthopaedic Institute, Tianjin Hospital, 406, Jiefang Nan Street, Hexi District, 300211 Tianjin, China.
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G
Xu
Biomechanics Labs of Orthopaedic Institute, Tianjin Hospital, 406, Jiefang Nan Street, Hexi District, 300211 Tianjin, China.
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X
Fu
Department of Orthopaedics, Binzhou Medical University Hospital, 661 Yellow River Road, 256603 Binzhou, China.
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C
Du
Biomechanics Labs of Orthopaedic Institute, Tianjin Hospital, 406, Jiefang Nan Street, Hexi District, 300211 Tianjin, China.
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J
Ma
Department of Orthopaedics, Tianjin Medical University General Hospital, 154 Anshan Street, Heping District, 300052 Tianjin, China; Department of Immunology, Tianjin Medical University, 22 Qixiangtai Road, Heping District, 300070 Tianjin, China.
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Z
Li
Biomechanics Labs of Orthopaedic Institute, Tianjin Hospital, 406, Jiefang Nan Street, Hexi District, 300211 Tianjin, China. Electronic address: spiritseeker2008@gmail.com.
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Ma
D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D006801:Humans; D008159:Lumbar Vertebrae; D016103:Spinal Fractures / Q000503:physiopathology / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods; D013904:Thoracic Vertebrae; D054854:Vertebroplasty
Finite element analysis; Posterior fixation; Thoracolumbar fracture; Vertebroplasty