• Kuhta P
• Owens EF Jr

• Atlanto-Occipital Joint

Methods: Forty nine patients were recruited for the study. Three x-ray analysis factors were tabulated: A/O Joint Difference, Lateral Mass Difference and Atlas Tips Difference. Subjects were between the ages of 18 and 58 and were already scheduled for an upper cervical radiographic series. A six-view cervical x-ray series was taken, consisting of a Neutral APOM, Right translation APOM, Left translation APOM, Nasium, Base Posterior, and Lateral cervical. For the translated APOMs, the patient translated his or her head to the right and left as far as comfortably possible. Three faculty doctors marked anatomical structures on the occiput and atlas and made three measurements related to the atlanto-occipital overlap.

Results: Inter-examiner reliability of the x-ray factors was substantial to almost perfect (ICC = .66 - .91) A One-way ANOVA showed a statistically significant relationship between head position and the A/O joint difference measure. Active head translation to the left produced an average change of 1.42 mm from neutral, and rightward translation resulted in an average 1.31 mm change in the A/O joint width difference (p<.001).

Discussion/Conclusion: Based on the results of this study, improper lateral head translation during radiographic setup can change the atlas laterality listing. Proper patient positioning and proper instruction of patients during positioning for the APOM and Nasium films should be strongly emphasized in chiropractic cervical radiographic positioning courses.

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