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Asymmetry in atlas bone specimens: a pilot study using radiographic analysis
John Hart1, Matt Christopher, Ralph Boone
1Assistant Director of Research, Sherman College of Straight Chiropractic, PO Box 1452, Spartanburg, SC 29304.
Journal of Chiropractic Medicine
|August 4, 2009
Summary
Vertebral asymmetry in atlas bones is common, with average bilateral differences of 0.96 mm. Radiographic measurements up to 1.63 mm can be considered normal variation, not misalignment.
Area of Science:
- Chiropractic
- Anatomy
- Biomechanics
Background:
- Vertebral asymmetries complicate the analysis of chiropractic vertebral subluxation.
- Accurate assessment of anatomical and biomechanical misalignment is crucial.
Purpose of the Study:
- To quantify the extent of asymmetry in natural atlas bone specimens.
- To establish a reference range for normal atlas asymmetry using radiographic analysis.
Main Methods:
- Digital radiography was used to image 10 natural atlas bone specimens.
- Two independent examiners evaluated the images using specialized software.
- Bilateral differences were analyzed for mean differences, standard deviations, and agreement.
Main Results:
- The mean bilateral difference between left and right atlas measurements was 0.96 mm (SD +/-0.67 mm).
- No statistically significant differences were found between left and right measurements.
- The average difference observed was 0.95 mm +/- 1 SD (0.67 mm).
Conclusions:
- Measurements up to 1.63 mm (1 SD) or 2.30 mm (2 SDs) fall within the normal variation for atlas asymmetry.
- Radiographic differences may represent natural asymmetry rather than actual misalignment.
- Clinicians should consider this reference range when assessing lateral atlas displacement to differentiate normal variation from subluxation.
