Comparison of the safety of three methods of lumbar transpedicular screw fixation

To choose a proper method of lumbar transpedicular screw fixation at different lumbar levels among the three methods (Roy-Camille's method, Magerl's method and Du's method) in the Chinese population.

Three-dimensional (3-D) images were reconstructed with image data of 42 adult lumbar segments that were scanned by Electron Beam CT. The three methods of lumbar pedicle screw fixation were simulated on the 3-D reconstructed images and the parameters of implanting pedicle screws were measured.

There was statistically significant difference at the distance from the entrance point to the pedicle axis between the three methods (P<0.001). The distances measured by Du's method were shortest from L1 to L4, and the distances measured by Magerl's method were shortest at L5 (P<0.05). There was no significant difference from L1 to L2 (P >0.05) but significant difference from L3 to L5 at inserting safe ranges of TSA (transverse section angle) was found between the three methods (P<0.05). From L3 to L4, the inserting safe ranges of TSA measured by Du's and Magerl's methods were significantly larger than that measured by Roy-Camille's method (P<0.05), but there was no significant difference between them (P>0.05). At L5, the inserting safe ranges of TSA measured by Magerl's method were largest among the three methods (P<0.05).

Among the three methods, Du's method is the best choice from L1 to L4 because its distance from the entrance point to the pedicle axis is shortest and the safe range of TSA is largest; Magerl's method can be used from L3 to L5 and is the best choice at L5; Roy-Camille's method is applicable at L1 and L2.