Use of 3D printer model to study vertebral artery anatomy and variations in developmental craniovertebral junction anomalies and as a preoperative tool-an institutional experience.

Abstract

Spinal instrumentation using rods and screws have become procedure of choice for posterior fixation. Vertebral artery anatomy is highly variable in this region posing challenges during surgery. Our study used 3D printer model to understand the anatomy and variations in vertebral artery in live patients thereby providing an accurate idea about vertebral artery injury risk in these patients preoperatively and to rehearse the whole procedure. Ten patients of developmental craniovertebral junction (CVJ) anomalies who were planned for operative intervention in the Department of Neurosurgery at SMS Hospital from February 2016 to December 2016 were analysed using a 3D printer model. Out of twenty vertebral arteries studied in ten patients, two were hypoplastic and out of these one could not be appreciated on 3D printer model. Out of remaining nineteen, thirteen arteries were found to lie outside the joint, three were in lateral third, one traversed the middle third of joint and one lied in medial third. In one patient, the vertebral artery was stretched and it traversed horizontally over the joint. Out of ten patients studied, nine were having occipitalised atlas and so entry of these vertebral arteries into cranium were classified as given by Wang et al. into four types. By our study, 3D printer model was extremely helpful in analyzing joints and vertebral artery preoperatively and making the surgeon acquainted about the placement and trajectory of the screws accordingly. In our opinion, these models should be included as a basic investigation tool in these patients.