Experimental flow characterization of PMMA bone cement in an artificial vertebra model

摘要

Introduction: In vertebroplasty, curing bone cement, such as PMMA (poly-methylmethacrylate), is injected into fractured vertebrae for stabilization and pain relief. While the procedure is effective, serious complications can arise from cement leakage into adjacent structures, which can lead to spinal cord compression or pulmonary embolism [1]. Since the properties of the cement play an important role in leak prevention [2], the flow behavior of PMMA was characterized as a function of injection speed, material viscosity and bone porosity. Injections were performed on an artificial vertebra model of known porosity, with the help of a computer-assisted injection device able to measure cement viscosity and provide constant injection speeds. Methods: The artificial vertebra model used in this experiment consists of two parts: A solid outer shell to simulate the cortical bone and an open-porous aluminum foam enclosed in the shell to mimic the trabecular structure. Three different foam porosities of 20, 30 and 40 pores per inch (PPI) were selected. The foam was filled with melted cow-butter to simulate bone marrow, as proposed in [3].