New fractures after vertebroplasty: adjacent fractures occur significantly sooner

Abstract

Background and purpose: Whether vertebroplasty increases the risk of adjacent-level vertebral fractures remains uncertain. Biomechanical and clinical studies suggest an increased risk, but compelling data have not yet been put forth to settle this difficult issue. We believe that an analysis of the time interval between vertebroplasty and subsequent fractures may shed additional light on this debate. We specifically hypothesized that subsequent fractures would occur sooner and more frequently in the vertebrae adjacent to the treated level.

Methods: We performed a retrospective analysis of the risk and timing of subsequent fractures in patients previously treated with vertebroplasty. Multiple linear regression was used to explore factors that influence the time to new fracture following vertebroplasty. Fractures were then divided on the basis of whether they occurred adjacent or non-adjacent to the treated level. Survival analysis was used to compare time to new fracture among the 2 groups, and the relative risk of both types of fracture was calculated.

Results: In this study, 186 new vertebral fractures occurred in 86 (19.9%) of 432 patients. Seventy-seven (41.4%) fractures were of vertebrae adjacent to the level treated with vertebroplasty. Median times until diagnosis of new adjacent and non-adjacent level fractures were 55 days and 127 days, respectively. Time to fracture was significantly different between the 2 groups (logrank <0.0001). Distance of the new fracture from the treated level was also significantly associated with time to new fracture (P < .0001). Relative risk of adjacent level fracture was 4.62 times that for non-adjacent level fracture.

Conclusion: These data demonstrate an association between vertebroplasty and new vertebral fractures. Specifically, following vertebroplasty, patients are at increased risk of new-onset adjacent-level fractures and, when these fractures occur, they occur sooner than non-adjacent level fractures.

Fig 1.

Location of prevalent and incident vertebral fractures. Two nonexclusive groups of incident fractures are shown—incident fractures following only the first vertebroplasty in a given patient and incident fractures following all vertebroplasties in a given patient. All data are shown as a percentage of that group of fractures. The distribution of prevalent fractures is bimodal with peaks around T8–T9 and T12–L1, with L1 as the most-common prevalent fracture location. The distributions of both groups of incident fractures were significantly different from the distribution of prevalent fractures with essentially a uniform distribution across the spine. There was no significant difference in the distributions of the 2 incident fracture groups.

Fig 2.

Distribution of prevalent and adjacent and nonadjacent incident fractures. The distribution of adjacent- and nonadjacent-level fractures is significantly different. Adjacent-level fractures predominate at the thoracolumbar junction (T11–L2), whereas nonadjacent-level fractures predominate in the midthoracic region of the spine (T7–T9).

Fig 3.

Survival curve depicting time incident of adjacent- and nonadjacent-level fractures in our patient population. Fractures adjacent to treated levels occur significantly sooner than fractures of nonadjacent vertebral bodies.

Fig 4.

Time from PVP to new fracture versus distance from PVP to new fracture. The distance from prior PVP to a new, incident fracture decreases as time from PVP to the incident fracture decreases as indicated by the simple linear regression line (estimate, 33.8; SE, 8.9; P = .0002).

Fig 5.

Survival curve depicting time to new fracture based on data from Uppin et al. Although not statistically significant, fractures of vertebrae adjacent to treated levels trend toward occurring sooner than fractures of nonadjacent levels.