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Quantitative anatomy of the second cervical vertebra
1Department of Orthopedic Surgery, Baylor College of Medicine, Houston, Texas, USA.
Spine
|March 1, 1995
Summary
Quantitative analysis of the second cervical vertebra reveals significant anatomical variation, particularly in dens angle. These findings highlight the need for precise measurements in modern spinal surgery due to a lack of correlation between key dimensions.
Area of Science:
- Anatomy
- Orthopedic Surgery
- Biomechanics
Background:
- Qualitative descriptions of the second cervical vertebra are insufficient for modern spinal pathology.
- Radiographic studies have limitations including magnification and projection errors.
- Previous direct measurements focused on dens morphology, neglecting lateral masses and the posterior ring.
Purpose of the Study:
- To directly measure clinically relevant dimensions of the second cervical vertebra.
- To provide quantitative anatomical data for surgical applications.
- To assess correlations between different vertebral dimensions.
Main Methods:
- Direct measurements of 51 dried human second cervical vertebrae using digital calipers and goniometers.
- Measured dimensions included dens diameters, end-plate and foramen diameters, and heights relative to specific anatomical landmarks.
- Dens angle in the sagittal plane was also assessed.
Main Results:
- Significant variation observed in dens angle (range: -2 to 42 degrees).
- Strong correlations found between total vertebral height and dens base height (r² = 0.81) and maximum dens lateral diameter (r² = 0.77).
- No significant correlation between dens height and spinal canal diameter was identified.
Conclusions:
- Confirms substantial anatomical variability in the second cervical vertebra.
- Demonstrates a lack of important correlations among measured dimensions, emphasizing individual anatomical differences.
- Dens angle in the sagittal plane is the most variable measured feature, crucial for surgical planning.