Quantitative Anatomy of Axis Vertebra in South Indian Population - Implications for Implant Design

Background: Cervical vertebra fractures following road traffic accidents and accidental fall are commonly encountered in Orthopaedic outpatient department and mandate fixation surgeries. The outcome of the surgeries is often compromised by the mismatch between the patient’s anatomy and implants designed using western anthropometric data. This study aimed to establish a comprehensive morphometric database for the second cervical vertebra-axis in South Indian population which can be used to design orthopaedic implants. Material and Methods: An observational study was conducted on 50 adult dry human Axis vertebra of both sexes from the collection at a tertiary care centre, in Tamil Nadu, India. Five key morphometric parameters were measured using standardized osteometric techniques with a digital vernier caliper. Results: The mean pedicle length, width, and height of the axis vertebra were 18.80 ± 1.82 mm, 9.98 ± 2.03 mm, and 8.50 ± 1.69 mm, respectively. The mean superior articular facet length and width were 15.38 ± 1.65 mm and 13.82 ± 1.24 mm, respectively. Compared with previous studies, the South Indian population demonstrated relatively shorter pedicle length and narrower superior articular facet width, while pedicle width and height were comparable to or greater than those reported in other populations. Conclusion: The morphometric profile of the South Indian Axis vertebra exhibits smaller dimensions when compared to North Indian and western population. This study emphasizes the necessity for developing population specific Axis implants to enhance geometric compatibility and therefore improve surgical outcomes.

Keywords: Axis vertebra fractures, population specific implants, South Indian population.