Analysis of adjacent vertebrae post vertebroplasty

Abstract

Vertebral Compression Fractures refer to the collapse of a vertebral body under excessive trauma to the spine. The surgical procedure to relieve pain and restore the normal height of the vertebral body is called vertebroplasty, in which a small amount of cement is injected into the spine. The problem with vertebroplasty is that the amount of cement injected is not accurate and leads to leakage into discs, which may develop into adjacent vertebral fractures. The current study aims at assessing the stress incurred on the adjacent vertebrae after vertebroplasty and the accurate cement levels required. The data in the form of CT images of the spine were acquired from a normal subject. A three-Dimensional model was generated by identifying the Regions of Interest (T11-L3), after performing volume and surface rendering techniques using Mimics and 3-MATIC. A force of 600 N was applied to the vertebrae for varying conditions of Bone Mineral Density (BMD), and the stress levels were calculated individually. Then, three fractures were induced at L1 and the corresponding 3-D models were generated. The stress levels on the fractured spine for forces of 600, 1200 and 1800 N were assessed. To assess the conditions after vertebroplasty, cement was injected in the fractured spine using Boolean Operations, which helped in optimizing the cement level. Results showed that the amount of cement required for the three cases were 4.5631, 5.5771 and 6.5849 mL respectively. Stress levels for the cement injected spine were analyzed, and were found to be much lesser than the stress incurred in the fractured cases with similar BMD. Among the adjacent vertebrae L2 was found to have a higher stress. Thus, this work seems to be clinically highly relevant in estimating the exact amounts of cements to be injected for different fracture cases thereby avoiding excessive cement leakage into the discs.