The temporal and spatial relationship between percutaneous vertebral augmentation and new symptomatic fractures

PURPOSE his study aimed to explore the relationship between the time from percutaneous vertebral augmentation (PVA) until subsequent fracture and the risk of new symptomatic fractures (NSFs) in untreated vertebrae at different distances from "augmented vertebrae". METHODS Patients who underwent PVA for the treatment of osteoporotic vertebral compression fractures at the West China Hospital of Sichuan University from May 2014 to April 2019 were retrospectively recruited. Vertebrae not treated during PVA were stratified based on their distance from the nearest augmented vertebra and the time elapsed since PVA. Survival curves were plotted to compare the risk of NSFs in untreated vertebrae at different distances from augmented vertebrae. The Cox proportional hazards model was used to identify risk factors of NSFs in untreated vertebrae. RESULTS In total, 162 patients with 228 NSFs (2.760 vertebrae) were analyzed. More than half of the NSFs (56.6%) occurred within the first year after PVA. Rates and hazard ratios (HRs) of NSFs were higher in vertebrae located one segment away from the augmented vertebrae (21.0%, HR: 3.99, P < 0.001), two segments away (10.6%, HR: 1.97, P = 0.003), or three segments away (10.5%, HR: 2.26, P < 0.001) than in vertebrae located five or more segments away (3.81%, HR: 1.00). Similar results were observed regardless of whether the untreated vertebrae were located in the thoracolumbar junction. In addition to distance, other risk factors of NSFs were the thoracolumbar location of untreated vertebrae, the number of augmented vertebrae, and percutaneous vertebroplasty. CONCLUSION The risk of NSFs is greater for untreated vertebrae located closer to augmented vertebrae than for untreated vertebrae further away. This distance dependence occurs mainly within the three segments closest to the augmented vertebra. The risk of NSFs decreases with time after augmentation, and it is also related to the number of augmented vertebrae, the type of augmentation, and whether the untreated vertebrae are thoracolumbar or not.