Morphometric Analysis of Vertebral Artery Groove in Human Atlas Vertebra in South Indian Population

ABSTRACT

Introduction: Recent trends like pedicle screws and other instrumentation of cervical vertebra are on the rise. However, proximity of vertebral artery coursing in vertebral artery groove (VAG) on the superior surface of the posterior arch of atlas poses a unique challenge to surgeons performing these procedures. Such vascular injuries though rare, are not uncommon and may pose immediate to delayed complications. Radiological studies of atlas vertebra & VAG are being extensively done with CT and MR Angiography, but morphometric studies of VAG in atlas vertebra in South Indian population is lacking. Aims: To understand the morphology and dimensions of the vertebral artery groove and its variations if any, in dry atlas vertebra of South Indian population. Settings and Design: Descriptive observational study Methods and Material: 50 dried adult human atlas vertebra of unknown age & sex from the Anatomy Department, PSGIMS & R, Coimbatorewere studied. Intact cervical vertebrae without any degenerative or traumatic disorders were included. The morphometry of VAG and its distance from midline were evaluated through six linear measurements.The parameters were inner and outer lengths of the groove, width & thickness of the groove and the distance of its medial most and lateral most edges from the midline on both sides. Statistical analysis used SPSS software Results: There is no statistically significant difference between mean values on right and left side for inner length, outer length, width and thickness of vertebral artery groove. The mean inner and outer distance of the vertebral artery groove from the midline on the right is higher than the left. Conclusions: The present study provides morphometric data of VAG & recommends a safe zone of 11.82 mm from midline for instrumentation in posterior spinal surgeries to minimize vertebral artery injuries.