1. Atlantoaxial Rotatory Fixation: New Diagnostic Paradigm And A New Classification Based On Motion Analysisi Using Computed Tomographic Imaging CGMH Chia Ni, Lin

2. Contents AARF Anatomy Patients and Method Result Discussion

3. Atlantoaxial Rotatory Fixation (AARF) The unique configuration of the atlantoaxial complex lends itself to behave as the main rotational pivot of the cervical spine often painful, rotational deformity that we call atlantoaxial rotatory fixation (AARF) because of its apparent “ fixed ” state to voluntary or involuntary correction. typically present with torticollis with the head in the “ cock-robin ” position

4. Anatomy

5. The predictable relationship between C1 and C2 single motion phase (from C1° = 0 to 23°), when only C1 turns double motion phase (from C1° = 24 to 65°) when both C1 and C2 are turning in the same direction Unison motion phase (from C1° = 65 to 90°)

6. Patient Exclusion Criteria The postinfectious cases associated with otological or pharyngeal infections Torticollis patients with congenital bony anomalies of the occipital-atlas-axis complex. Within the posttraumatic group, cases with concomitant atlanto-occipital and other cervical fracture dislocations and spinal cord injury without radiographic abnormality.

7. Clinical information

8. Image technique All angle measurements :axial CT scans using bone algorithms the lower half of the clivus to the base of the C3 body, 3 mm thick without overlap at a 0-degree gantry angle (120kV, 70 mA, with a 2-second scan time) Mild sedation

9. Angle measurements

10. Normal template

11. Group 1 patients

12. Type I AARF

13. Type I AARF (Patient 4, Group 1)

14. Motion Curve of all Group 1 Patients

15. Group 2 patients

16. Type II AARF (Patient 5, Group 2)

17. Type II AARF

18. Motion Curve of all seven Group 2 Patients

19. Group 3 patients

20. Type III AARF (Patient 8, Group 3)

21. Type III AARF

22. Motion Curve of all nine Group 3 Patients

23. Group 4 patients

24. Motion Curve of all 14 Group 4 Patients

25. Group 5 patients

26. Motion Curve of all five Group 5 Patients

27. Rough diagnostic domains of the three type of AARF

28. Case 1

29. Case 2

30. Summary

31. Diagnostic paradigm of AARF

32. Discussion The more horizontal the curve, the more locked are the two bones Diagnostic curve.

34. Management algorithm of AARF