Biomechanical study of posterior occipital condylar screw internal fixation system

English Keywords:Occipitocervical fusion  Occipital condyle screws  Biomechanics

English Abstract:

  【Abstract】 Objectives: To provide experimental basis for the occipital condyle screw technique through a biomechanical analysis. Methods: The normal model, instability model and occipital condyle screw fixation model were built respectively, 6 fresh craniocervical(C0-C4) specimens were screened by CT scan. 1.5 N·m torque was added at flexion, extension, lateral flexion and rotation direction, and then their relative range of motion(ROM) was measured. Finally, the validity of the occipital condylar screw fixation techniques was evaluated by comparing their range of motion(ROM). Results: The ROMs(C0-C1) of the normal model were 14.13°±0.71°, 7.60°±0.43°, 3.77°±0.27°, 5.42°±0.44° in flexion, extension, lateral bending and rotation, respectively. The ROMs of instability model were 23.57°±2.26°, 11.96°±1.44°, 5.21°±0.29°, 7.13°±0.67°, and those of the occipital condyle screw fixation model were 7.53°±0.77°, 3.79°±0.64°, 2.56°±0.34°, 0.89°±0.31°.Similarly in the C0-C2 segments, the ROMs of the normal model were 19.72°±0.71°, 17.62°±0.97°, 7.55°±0.51°, 51.46°±3.11° respectively, the instability model′s were 30.57°±2.32°, 23.85°±0.91°, 9.37°±0.55°, 68.91°±6.25°, and those of the occipital condyle screw fixation model were 11.30°±0.66°, 9.19°±0.63°, 5.12°±0.59°, 7.39°±0.76°. The ROM of the instability model is largest and the normal model is larger than the occipital condyle screw fixation model. Conclusions: The occipital condyle screw fixation technology can reduce the ROM(C0-C1, C0-C2), which is reliable in clinical practice.