Abstract:

Objective　to study three methods of lumbar pedicle placement in different level based on CT tomographic image reconstruction model in order to determine the location of "∧" shape crest of the Lumbar vertebra and provide objective basis.　Methods　In 30 cases of lumbar CT three-dimensional reconstruction model, the placement of the screw was simulated, using the method of the "∧ "shape crest, the method of above the "∧ "shape crest and the method of below the "∧ "shape crest, the distance between screw entry point and the pedicle axis was measured, and the anatomic relationship between the upper and lower edges, the internal and the external edges was studied. Differences, advantages and disadvantages of three methods at each segment of lumbar were analysed.　Results　The anatomic relationship between  "∧ "shape crest and lumbar pedicle was different in the three methods. The distance between "∧ "shape crest and the pedicle axis was shortest in the median sagittal plane, but was slightly higher than pedicle axis in the L1, and was slightly lower than the horizontal axis in L5 . The Upper "∧ " shape crest was located above the pedicle axis. Only in 2 cases Upper "∧ " shape crest was lower than the pedicle axis in the L5.　Conclusion　in the lumbar pedicle screw fixation, "∧ "shape crest method is safe and reliable, applicable to L1~ L5. But in L1 the screw in the median sagittal plane is slightly higher than the pedicle axis, and was slightly lower the axis of the pedicle in L5 .

Key words: "&and, "shape crest, Pedicle screw, CT, Three dimensional reconstmctio