50 research outputs found
Estudo da influência do torque de inserção na resistência ao arrancamento dos parafusos pediculares
Utilización de un nuevo tornillo expansivo en pacientes con mala calidad ósea: estudio multicéntrico
Comparison between two pedicle screw augmentation instrumentations in adult degenerative scoliosis with osteoporosis
Influência do diâmetro do orifício piloto na resistência ao arrancamento dos parafusos do corpo vertebral
Role of ‘low cost Indian implants’ in our practice: our experience with 1,572 pedicle screws
Biomechanical comparison of sagittal-parallel versus non-parallel pedicle screw placement
Effects of lumbar disc surgery on bone mineral density in women with lumbar disc disease
A biomechanical analysis of the self-retaining pedicle hook device in posterior spinal fixation
Regular hooks lack initial fixation to the spine during spinal deformity surgery. This runs the risk of posterior hook dislodgement during manipulation and correction of the spinal deformity, that may lead to loss of correction, hook migration, and post-operative junctional kyphosis. To prevent hook dislodgement during surgery, a self-retaining pedicle hook device (SPHD) is available that is made up of two counter-positioned hooks forming a monoblock posterior claw device. The initial segmental posterior fixation strength of a SPHD, however, is unknown. A biomechanical pull-out study of posterior segmental spinal fixation in a cadaver vertebral model was designed to investigate the axial pull-out strength for a SPHD, and compared to the pull-out strength of a pedicle screw. Ten porcine lumbar vertebral bodies were instrumented in pairs with two different instrumentation constructs after measuring the bone mineral density of each individual vertebra. The instrumentation constructs were extracted employing a material testing system using axial forces. The maximum pull-out forces were recorded at the time of the construct failure. Failure of the SPHD appeared in rotation and lateral displacement, without fracturing of the posterior structures. The average pull-out strength of the SPHD was 236 N versus 1,047 N in the pedicle screws (P < 0.001). The pull-out strength of the pedicle screws showed greater correlation with the BMC compared to the SPHD (P < 0.005). The SPHD showed to provide a significant inferior segmental fixation to the posterior spine in comparison to pedicle screw fixation. Despite the beneficial characteristics of the monoblock claw construct in a SPHD, that decreases the risk of posterior hook dislodgement during surgery compared to regular hooks, the SPHD does not improve the pull-out strength in such a way that it may provide a biomechanically solid alternative to pedicle screw fixation in the posterior spine