Biomechanical evaluation of the long U-shaped hollow pedicle screw system for percutaneous fixation of thoracolumbar fractures / 中华创伤骨科杂志

ABSTRACT

Objective To evaluate the biomechanical characteristics of the long U-shaped hollow pedicle screw system for percutaneous fixation of thoracolumbar fractures.Methods Models of vertebral compression fracture were created by flexion in 8 fresh cadaveric samples of thoracolumbar spine.The models were divided into 2 equal groups according to the fixation system applied.In group A conventional pedicle screws were used while in group B long U-shaped hollow pedicle screws were used.The yield compressive strength,axial compression stiffness,bending stiffness,torque and torsional stiffness of all the fixated spines in the 2 groups were tested by the bio-mechanical electrical measurement and compared as well.Results The conventional pedicle screws and long U-shaped hollow pedicle screws showed no significant differences regarding yield compressive strength (3450.02 ± 110.03 MPa vs.3430.04 ± 102.12 MPa),axial compressionstiffness (407.52 ± 33.02 N/mm vs.395.04 ± 26.46 N/mm),bending stiffness (305.14 ± 26.53 N · cm/Degvs.295.12±23.80 N · cm/Deg),torque (6.45±0.25 N · m vs.6.25±0.21 N · m) or torsional stiffness (0.54±0.04N·cm/Degvs.0.52±0.03N·cm/Deg) (P＞ 0.05).Conclusion The long U-shaped hollow pedicle screw system can satisfy the biomechanical requirements for fixation of thoracolumbar fractures and can function as well as the conventional pedicle screw system.