To improve the lumbar stability after operation, inserting bi-cortical pedicle screws in the vertebrae is viable when the patients associated with osteoporosis. But the bi-cortical pedicle screws improperly invert may lead to serious complications such as spinal cord, nerve root, abdominal aorta, inferior vena cava and organs damage. So it is important to measure the parameters of inverting the screws pre-operation.OBJECTIVE:
To measure the preoperative individual parameters of inserting bi-cortical pedicle screws in the lumbar vertebrae with CT and digital orthopedic technique.METHODS:
The image data of L1-4 that scanned by CT was imported into the Mimics 10.0 software and GE workstation, and L1-4 three-dimensional image was reconstructed. The individual parameters of inserting bi-cortical pedicle screws in the L1, 3 were measured.RESULTS AND CONCLUSION:
The three-dimensional CT lumbar image was reconstructed clearly, and the placement of bi-cortical pedicle screws on the crista lambdoidalis was simulated by Mimics 10.0 software. The minimum diameter, sagittal angle of simulated inserting bi-cortical pedicle screws, leaning angle (horizontal angle) and the horizontal depth were measured by the Mimics 10.0 software. Meanwhile, the limited depth of the screws when parallel to vertebral end-plate was calculated. It is a reliable method to get individual parameters of inserting bi-cortical pedicle screws in the lumbar vertebrae and it can improve the safety and accuracy of screw fixation.