BACKGROUND:In clinic, monosegmental pedicle screw fixation via the fractured vertebrae is commonly used for the treatment of thoracolumbar fracture. Studies have confirmed that the spinal stability is strengthened through bilateral pedicle screw fixation via fractured vertebrae, but some studies suggest that monosegmental pedicle screw fixation via fractured vertebrae can increase the spinal stability, and the conclusion lacks of the supports of biomechanics.
OBJECTIVE:To evaluate the biomechanical properties of monosegmental pedicle screws fixation via fractured vertebrae for thoracolumbar fracture.
METHODS:Eight cadavers’ thoracolumbar specimens (T11-L3) were provided by the Department of Anatomy, Yangzhou University School of Medicine. Saw was used to transect 2/3 of the vertebrae in order to make complete experimental thoracolumbar specimens. Eight specimens were divided into two group;beyond-fractured vertebrae fixation group and monosegmental fixation via fracture vertebrae group. The specimens in the two groups were treated with adjacent vertebral four screw fixation beyond fractured vertebrae and adjacent vertebral four screw fixation+monosegmental pedicle screw fixation via fractured vertebrae respectively.
RESULTS AND CONCLUSION:After thoracolumbar fracture, the differences between beyond fractured vertebrae fixation and monosegmental pedicle screw fixation via fractured vertebrae were as fol ows:load-strain relationship 12%, load-displacement relationship 11%, strength 18%, axial rigidity 11%, torsional mechanical properties 11%and pul out test 1.8%, and there were no significant differences between two groups (P<0.05). The biomechanics performance of monosegmental pedicle screw fixation via fractured vertebrae was more superior to that of pedicle screw fixation beyond the fracture vertebra for thoracolumbar fracture.