Morphometric analysis of axis vertebra on MRI

Pathan F J^1*, Rubeena Hashmi²

Abstract               Background: Features of the axis vertebra are atypical with respect to shape and its anatomical and biomechanical properties are unique. The cervical region and lumbar region are most prone for orthopedic problems Aims and Objectives: to study morphometric Analysis of Axis Vertebra on MRI. Methodology: This was a cross-sectional study carried out in the apparently normal individuals undergone MRI for neck included into the study over a six month period i.e. January 2018 to June 2018 in the six month period 50 males and 50 females were included into study. In this all of the individuals undergone MRI of neck with standard protocols. The data entered excel sheets and analyzed by un-paired t-test calculated by SPSS 19 version software. Result: In males the Body of Axis the mean±SD in mm - AP diameter was -13.2± 0.42; Transverse was 17.96±0.87; Ant. height was 9.64± 0.38; Post. Height was 9.06± 0.56. In Dense axis it was, AP diameter -7.61 ±0.19, Transverse- 7.60 ± 0.20; Vertical-15.79 ± 0.87; Vertebral canal–AP Was 12.40 ± 0.55, Transverse was 18.64 ± 0.77. In Females the Body of Axis the mean±SD in mm - AP diameter was -13.17± 0.59; Transverse was 18.01±0.94; Ant. height was 9.37± 0.59; Post. Height was 8.88± 0. 58. In Dense axis it was, AP diameter -7.50 ±0.29, Transverse- 7.55 ± 0.42; Vertical-15.41 ± 1.02; Vertebral canal – AP Was 11.99 ± 0.94, Transverse was 18.30 ± 1.31. In the morphometric analysis the all parameters of Body Axis like – AP diameter(t=0.29,df=98,p>0.05), Transverse diameter(t=0.62,df=98,p>0.05), Ant. Height (t=0.72,df=98,p>0.05), Post. Height(t=1.49,df=98,p>0.05); Dense of axis-AP(t=0.19,df=98,p<0.05 ), Transverse(t=0.82,df=98,p<0.05), Vertical (t=1.23,df=98,p>0.05) Vertebral canal- Transverse(t=1.19,df=98,p>0.05) were comparable with each other except Vertebral canal AP diameter where it was more among the males as compared to females (*t=2.59,df=98,p<0.01) Conclusion: Morphometric Analysis of Axis Vertebra is useful for as reference in the cervical surgeries and for the diagnosis of orthopedic problems of neck in that morphology of axis vertebra is crucial and is very useful.

Key Word: Axis Vertebra, MRI, Morphometry.

INTRODUCTION

Features of the axis vertebra are atypical with respect to shape and its anatomical and biomechanical properties are unique. The cervical region and lumbar region are most prone for orthopedic problems¹. The fractures of the dens axis is common as the third of all cervical vertebrae fractures^2,3. However, surgeries in this region are highly risky for possible damage to aorta or other adjacent vital structures ^4,6. Thus the dimensions of instrumentations and their insertion need to respect anatomical features of the vertebra. Not only for treatment of vertebral diseases and instabilities, but also for diagnoses, the knowledge of the exact vertebral dimensions is crucial. As the ethnical variation in the vertebral dimensions has been reported, it is also necessary to distinguish the patient origin^7,9. For this reason we have Morphometric Analysis of Axis Vertebra on MRI

METHODOLOGY

This was a cross-sectional study carried out in the apparently normal individuals undergone MRI for neck included into the study over a six month period i.e. January 2018 to June 2018 in the six month period 50 males and 50 females were included into study. In this all of the individuals undergone MRI of neck with standard protocols. In the MRI findings we have done morphometric analysis of Axis Vertebra with respect to Body Axis–AP and Transverse diameter, Ant. height ,Post. Height; Dense of axis –AP, Transverse diameter, Vertical height; Vertebral canal–AP and Transverse diameter etc. the data entered excel sheets and analyzed by un-paired t-test calculated by SPSS 19 version software.

 RESULT

Table 1: Morphometric analysis of Axis Vertebra in the male patients

In males the Body of Axis the mean±SD in mm - AP diameter was -13.2± 0.42; Transverse was 17.96±0.87; Ant. height was 9.64± 0.38; Post. Height was 9.06± 0.56. In Dense axis it was, AP diameter -7.61 ±0.19, Transverse- 7.60 ± 0.20; Vertical-15.79 ± 0.87; Vertebral canal–AP Was 12.40 ± 0.55, Transverse was 18.64 ± 0.77

Table 2: Morphometric analysis of Axis Vertebra in the female patients

In Females the Body of Axis the mean±SD in mm - AP diameter was -13.17± 0.59; Transverse was 18.01±0.94; Ant. height was 9.37± 0.59; Post. Height was 8.88± 0.58. In Dense axis it was, AP diameter -7.50 ±0.29, Transverse- 7.55 ± 0.42; Vertical-15.41 ± 1.02; Vertebral canal – AP Was 11.99 ± 0.94, Transverse was 18.30 ± 1.31.

Table 3: Comparison of the morphometric parameters in Males and Females

In the morphometric analysis the all parameters of Body Axis like – AP diameter(t=0.29,df=98,p>0.05), Transverse iameter(t=0.62,df=98,p>0.05), Ant. Height (t=0.72,df=98,p>0.05) , Post. Height(t=1.49,df=98,p>0.05) ; Dense of axis-AP(t=0.19,df=98,p<0.05),Transverse(t=0.82,df=98,p<0.05),Vertical(t=1.23,df=98,p>0.05)VertebralcanalTransverse(t=1.19,df=98,p>0.05) were comparable with each other except Vertebral canal AP diameter where it was more among the males as compared to females (*t=2.59,df=98,p<0.01)

DISCUSSION

Axis vertebra has various distinct anatomical features like dens or odontoid process, two lateral masses with obliquely oriented articulating facets, transverse processes with foramina transversarium d spinous process. It is related to various vital
and a usually bi structures like the cervico-medullary junction, cranial nerves, cervical spinal nerve roots and vertebral arteries. Various pathological processes like congenital skeletal dysplasias, trauma, infection, neoplasm etc. affect the axis vertebra^9-15The morphological characteristics of axis vertebra are crucial in managing various pathologies of the craniovertebral junction¹⁶.Various anatomical features of axis vertebra make it unique and hence variations in morphological parameters assume importance. Varied surgical procedures are performed to address the pathologies of the craniovertebral junction such as interlaminal clamping, interspinous xation etc. wiring, plate and screw  In our study we have seen that In males the Body of Axis the mean±SD in mm - AP diameter was -13.2± 0.42; Transverse was 17.96±0.87; Ant. height was 9.64± 0.38; Post. Height was 9.06± 0.56. and in In Females the Body of Axis the mean±SD in mm-AP diameter was -13.17± 0.59; Transverse was 18.01±0.94; Ant. height was 9.37± 0.59; Post. Height was 8.88± 0.58.  In the study by Sneha et al found the mean height of body of axis vertebra was 16.33+1.76mm, being 16.93+1.63 mm in males and 15.8+1.7mm in females. Singla et al. found that the mean anterior height of body of axis was 19.67 mm¹⁷. Lang¹⁸ measured the same parameter with its value 22.1mm and Lu et al.,¹⁹ found this parameter as 20.4 mm. In our study, the mean height of body of axis vertebra was16.33+1.76 mm, which is less than that found in previous studies In males Dense axis it was, AP diameter -7.61 ±0.19, Transverse- 7.60 ± 0.20; Vertical-15.79 ± 0.87; Vertebral canal – AP Was 12.40 ± 0.55, Transverse was 18.64 ± 0.77  In females Dense axis it was, AP diameter -7.50 ±0.29, Transverse- 7.55 ± 0.42; Vertical-15.41 ± 1.02; Vertebral canal – AP Was 11.99 ± 0.94, Transverse was 18.30 ± 1.31.  In study by Sneha ²⁰ et al found the mean AP and transverse diameter of dens was 10.82 +0.99 mm and 9.8 +1.25 mm respectively, being 11.1+0.81 mm and 10.15 +1.41 mm in males and 10.58 +1.07 mm and 9.50 +1.02 mm in females respectively. The number of subjects who had the minimum transverse diameter less than 9 mm were 35 % [10 males (21.7%), 25 females cantly more in females (p=0.01). The number of (46.2 %)] being significant subjects having minimum transverse diameter less than 7.4 mm were 2 % [0 males, 2 females (3.7 %)].In the morphometric analysis the all parameters of BodyAxislikediameter(t=0.29,df=98,p>0.05),Transversediameter(t=0.62,df=98,p>0.05),Ant.Height(t=0.72,df=98,p>0.05),Post.Height(t=1.49,df=98,p>0.05);DenseofaxisAP(t=0.19,df=98,p<0.05),ransverse(t=0.82,df=98,p<0.05),Verticalt=1.23,df=98,p>0.05) Vertebral canal- Transverse(t=1.19,df=98,p>0.05) were comparable with each other except Vertebral canal AP diameter where it was more among the males as compared to females (*t=2.59,df=98,p<0.01) Except Vertebral canal- Transverse all other parameters in males and Females in our study were comparable this could be due to the geographic variation in the individuals.

CONCLUSION

Morphometric Analysis of Axis Vertebra is useful for as reference in the cervical surgeries and for the diagnosis of orthopedic problems of neck in that morphology of axis vertebra is crucial and is very useful

REFERENCES