ABSTRACT
BACKGROUND:Santoni put forward the cortical bone trajectory technology by changing the traditional pedicle screw placement for lumbar internal fixation in order to obtain better control of the screw and bone in 2009. OBJECTIVE:To analyze biomechanical stability of cortical bone trajectory system in the lumbar fusion. METHODS:Twenty fresh newborn calf L3/4, L5/6 motion segment specimens were obtained, and their ranges of motion were detected under different states, as normal controls. Subsequently, twenty samples were divided into cortical bone trajectory screw group and traditional pedicle screw group, which underwent cortical bone trajectory screw fixation combined with posterior lumbar fusion and traditional pedicle screw fixation combined with posterior lumbar fusion, respectively. Without destruction, ranges of motion were detected under different states in both groups. In the revision group, after the test in the traditional pedicle screw group, screw was withdrawn, and cortical bone trajectory screw was used to detect its range of motion under different states. RESULTS AND CONCLUSION:Ranges of motion at bending to the left and right, anteflexion, posterior extension and axial rotation were significantly lower in the cortical bone trajectory screw group and traditional pedicle screw group than in the normal control group (P0.05). These results confirmed that cortical bone trajectory technology combined with posterior lumbar fusion can obtain identical stability as the traditional pedicle screw fixation combined with posterior lumbar fusion. Simultaneously, it is a new choice for revision after traditional pedicle screw fixation.
ABSTRACT
Between June 2008 and June 2013, our department treated 16 severe thoracolumbar fracture dislocations (13 male and three female patients; mean age 33.6 years) with a pedicle screw system via an entirely posterior approach. We followed all patients for 18-69 months (mean 35 months). The mean operation time was 170 minutes (range: 120-280), and mean blood loss was 700 ml (range: 450-1300). The percentage displacement (mean ± standard deviation) improved from a preoperative value of 72 ± 20% to 10 ± 6% postoperatively, and the deformity angle (mean ± standard deviation) improved from 29.2 ± 15.0° to 12.6 ± 6.7°. Of the six patients with American Spinal Injury Association Grade A, one improved to Grade B, one to Grade C and four had little improvement. Of the five patients with Grade B, three improved to Grade C and two to Grade D. Of the four Grade C patients, two improved to Grade D, and the other two to Grade E. One Grade D patient improved to Grade E. No loosening or breakage of the internal implants occurred in the follow-up period. Therefore, we conclude that although it is difficult, the posterior approach alone is safe and biomechanically reliable for treating severe thoracolumbar fracture dislocations. The maintenance of deformity correction and stable local mechanical reconstruction in the follow-up period support this single approach strategy.
