Raman Mohan Sharma
J.N.Medical College, India
Title: Morphometric and radiological assessments of dimensions of Axis in dry vertebrae A study in South Asian Population
Biography
Biography: Raman Mohan Sharma
Abstract
Purpose
The technique of intralaminar screw placement for achieving axis (C2) fixation has been recently described. The purpose of the study was to provide the morphometric and radiological measurements in Indian population and to determine the feasibility of safe translaminar screw placement.
Materials and Methods
38 dry axis vertebrae from adult South Indian population were subjected to morphometric and CT scan analysis. Height of posterior arch, midlaminar width in upper 1/3rd, middle 1/3rd and lower 1/3rd were measured using high precision Vernier Calipers. Each vertebra was subjected to a spiral CT scan , thin 0.5 mm slices were taken and reconstruction was done in coronal and sagittal plane. Analysis was done on a CT work station.
Results
Middle 1/3rd lamina was the thickest portion (mean 5.17 mm +/‑.1.42 mm). A total of 32 (84.2%) specimen were having midlaminar width in both lamina greater than 4 mm, however only 27 (71%) out of them had spinous process more than 9 mm. CT scan measurement in middle and lower 1/3rd lamina was found to be strongly correlated with the direct measurement.
Conclusion
There is high variability in the thickness of the C2 lamina. As compared to western population, the axis bones used in the present study had smaller profiles. Hence the safety margin for translaminar screw insertion is low.