Estimating risk of pulmonary neoplastic embolism during vertebroplasty

Abstract

Study design: Vertebroplasty was simulated on a pig model.

Objective: To evaluate the risk of neoplastic tissue migration into lungs during vertebroplasty.

Summary of background data: The application of vertebroplasty in spinal metastasis is not well documented. The risk of neoplastic tissue migration into the lungs during vertebroplasty remains unknown.

Methods: A cancer model was built in 11 Landrace pigs (50 kg) by injecting 99mTc-labeled albumin macroaggregates into the center of L5 and L6 prior to vertebroplasty. Continuous scintigraphic imaging was performed with 1-minute frames over the lungs and vertebrae before and after injection to ensure steady state and baseline. We surveyed free TcO4- in thyroid. Twenty minutes after the 99mTc injection, 2-level vertebroplasty was performed at L5 and L6 with 3 Jamshidi needles in each vertebra. Into each vertebra, on average, 2.8 ± 1.1 mL of poly(methyl methacrylate) cement (Depuy CMW, Blackpool, UK) was injected. Quantitative scintigrams were obtained within 90 minutes after vertebroplasty. X-rays and quantitative computed tomography scans quantified cement distribution. Means of 99mTc activity before and after vertebroplasty were compared in a paired t test.

Results: In this cancer model, we found an 80% risk of tissue migration to the lungs when performing vertebroplasty. In average, the study showed a significant amount of macroaggregate migration of 1.87% total range from 0% to 8% (CI: 0.05%-0.37%) with P = 0.045. There was no free TcO4- in the thyroid. Despite the standardized procedure, we found a large interindividual variation of pulmonary embolism.

Conclusion: It is demonstrated that there exists a significant risk of exporting neoplastic disease or fatty tissue to the lungs when performing vertebroplasty. A similar adverse effect can be expected with balloon kyphoplasty. In patients with metastatic disease, vertebroplasty should be limited to those with short life expectancy.