RESUMEN
OBJECTIVE: To determine the three-dimensional stability of C1-C2 after anterior approach screw fixation through C2 vertebral body to C1 lateral mass for C1-C2 instability or dislocation. METHODS: The three-dimensional range of motion of atlantoaxial joint were measured in 16 human cadaveric specimens under four conditions: the intact state (1st group), odontoid fracture of type II (2nd group), instrumentation with posterior C1-C2 trans-articular screw fixation (Magerl technique) (3rd group) and anterior approach screw fixation through C2 vertebral body to C1 lateral mass (4th group) respectively. RESULTS: There was generally significant difference between 1st group and other groups and between 2nd group and other groups by statistics analysis (P < 0.001). Range of motion significantly decreased in 3rd group and 4th group in all directions. There was generally no significant difference between the two methods by statistical analysis (P > 0.05). CONCLUSION: Anterior approach screw fixation through C2 vertebral body to C lateral mass provides satisfied stability. It provides the equivalent effect to Magerl technique. It is a kind of reliable surgery choice for the treatment of instability or dislocation of C1-C2 joint.