Biomechanical study on the stability of atlantoaxial transarticular screw combined with atlas pedicle screw fixation technique

English Keywords:Atlas fracture  Pedicle screw  Atlantoaxial transarticular screw  Biomechanics

English Abstract:

  【Abstract】 Objectives: To investigate the advantages and disadvantages of atlas pedicle screw combined with atlantoaxial transarticular screw fixation technique over other commonly used atlantoaxial fixation techniques in terms of mechanical stability. Methods: Six fresh specimens of adult cervical spine were used to prepare an intact model of the upper cervical spine(intact group), and the range of motion(ROM) values of C1-C2 in flexion-extension, lateral bending and rotation at a torque of 1.5Nm were measured using biomechanical testing instruments and computer visual analysis software. The anterior arch and lateral mass of atlas were destroyed to prepare the unstable model(unstable group), and measure the ROM values of C1-C2 in each direction under the same torque again. The atlas pedicle screw + axial pedicle screw fixation(C1P+C2P group), atlas pedicle screw + atlantoaxial transarticular screw fixation(C1P+TA group), and atlantoaxial transarticular screw fixation alone(TA group) were prepared in sequential order, and the ROMs in each direction were measured under the same torque, and the differences in C1-C2 ROMs between the groups were compared. Results: The unstable group had greater ROM in six directions than the intact group, and there was a significant difference in ROM in all directions between the two groups(P<0.05); the C1P+C2P group, C1P+TA group, and TA group had significant decreases in ROM compared with the unstable group(P<0.05); the ROM values in the flexion, extension, left and right rotation directions were statistically different between the three fixation groups(P<0.05), with the C1P+TA group