how to determine the permeability for Cement infiltration of Osteoporotic Cancellous Bone.pdf

Medical Engineering Physics 25 (2003) 283–288 /locate/medengphy How to determine the permeability for cement infiltration of osteoporotic cancellous bone G. Baroud a,? , J.Z. Wu b , M. Bohner c , S. Sponagel d , T. Steffen a a McGill University, Orthopaedic Research Laboratory, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC HAS 1A1, Canada b National Institute for Occupational Safety Health, Morgantown, West Virginia 26505, USA c Dr. H. C. Robert Mathys Foundation, 2544 Bettlach, Switzerland d University of Applied Science of Aachen (FH), Biomedical Engineering, Ju?lich, Germany Received 7 May 2002; received in revised form 7 October 2002; accepted 31 October 2002 Abstract Cement augmentation is an emerging surgical procedure in which bone cement is used to infiltrate and reinforce osteoporotic vertebrae. Although this infiltration procedure has been widely applied, it is performed empirically and little is known about the flow characteristics of cement during the injection process. We present a theoretical and experimental approach to investigate the intertrabecular bone permeability during the infiltration procedure. The cement permeability was considered to be dependent on time, bone porosity, and cement viscosity in our analysis. In order to determine the time-dependent permeability, ten cancellous bone cores were harvested from osteoporotic vertebrae, infiltrated with acrylic cement at a constant flow rate, and the pressure drop across the cores during the infiltration was measured. The viscosity dependence of the permeability was determined based on published experimental data. The theoretical model for the permeability as a function of bone porosity and time was then fit to the testing data. Our findings suggest that the intertrabecular bone permeability depends strongly on time. For instance, the initial permeability (60.89 mm 4 /N ? s) reduced to approximately 63% of its original value within 18 seconds. This study is the first to analyze cem