Biomechanical evaluation of posterior atlanto-occipital clivus screw fixationtechniques / 中华骨科杂志

ABSTRACT

Objective:To provide a theoretical basis for the clinical application of the posterior route through atlas occipital articular slope screw internal fixation system through the biomechanical study.Methods:Eight cadavers of healthy adults aged 35-60 years and 155-180 cm in height were selected. The specimens with complete anatomical structure and without surgical operation were established as normal models. The model of occipito-atlantoaxial complex was established by breaking the articular capsule, ligament and other connecting structures and cutting the dentate process. The device was established as an internal fixation model through the specimen of atlantooccipital joint slope screw internal fixation system. Given normal model and internal fixation of 1.5 N·m in the moment of flexion, lateral bending and axial rotation and to measure the specimen C 0-C 1 and C 0-C 2 segment of the range (range of motion, ROM), comparative analysis of pillow neck area within the normal model and fixed model changes the range of movement, after the evaluation through the slope between atlas and the occipital screw internal fixation system of mechanical properties. Results:In the normal model, the flexion, flexion and extension, lateral bend and axial rotation ranges of C 0-C 1 segments were 23.85°±2.43°, 4.74°±0.55°, 5.77°±0.75°, respectively; the corresponding activity ranges of C 0-C 2 segments were 30.66°±3.05°, 9.09°±1.37°, 70.97°±9.48°, respectively; in the internal fixation model, the flexion and extension, lateral bend and axial rotation ranges of C 0-C 1 segments were 0.71°±0.24°, 0.24°±0.06°, 0.34°±0.09°, respectively. The corresponding activity range of C 0-C 2 segment was 3.09°±0.82°, 0.74°±0.07°, 1.22°±0.10°, respectively. Compared with the normal model, the range of activity of the internal fixation model in all directions was significantly reduced (<3°), and the reduction ratio of activity was more than 90%. Conclusion:The posterior route through pillow slope screw internal fixation system can effectively reduce the range of motion of the occipital neck in flexion, extension, lateral bending and rotation, and has safe and reliable biomechanical stability.