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Meta-Analysis Comparing the in vivo Cement Extravasation Rates for Vertebroplasty and Kyphoplasty 2004

Agris, Jacob,M.D. Hussain, Namath, M.D., Gailloud, Philippe, Murphy, Kieran, M.D.

Purpose:
Osteoporotic compression fractures have been treated by vertebroplasty for more than 15 years and kyphoplasty in the past 4 years. Kyphoplasty was purported to reduce complications by reducing extravasation. This was not supported by prior cadaveric results by Agris et al, so a meta analysis of all published in vitro results with reported extravasation rates was performed.

Methods:
A literature search was performed back to Deramond's original report in 1987 identifing all case series of vertebroplasty and kyphoplasty, for benign osteoporotic compression fracture,s that reported their cement extravisation rates , including those from our institution.

Results:
Nine peer reviewed publications on vertebroplasty and five on kyphoplasty were identified. This included a total of 1267 vertebroplasty and 315 kyphoplasty patients. There were 123 and 37 reports of venous extravasations, respectively. This resulted in extravisation rates of 9.7% for vertebroplasty and 11.7% for kyphoplasty. Regression analysis demonstrated that larger series tended to demonstrated lower extravasation rates. A weighted ANOVA model demonstrated that there was a statistically significant difference in the rates of extravasation (p<0.10).

Conclusion:
Lower cement extravasation rates are reported with vertebroplasty when compared to kyphoplasty. Additionally, some vertebroplasty studies used CT rather than fluoroscopy to evaluate for extravisation which would likely result in underestimation bias of the actual kyphoplasty extravasation rates. Furthermore, kyphoplasty requires an initial balloon inflation that may cause marrow element extravasation that can not be detected by fluoroscopy. Therefore higher complication rates might be expected by kyphoplasty, but it is difficult to determine from the literature given the smaller number of reported procedures and 83% of the reported cases are reported by one publication from a single center.