Characterization of Thermal Properties of Polymethylmethacrylate Bone Cement for Therapeutic Ultrasound Application

Biomaterials interact with biological systems and are intended to replace tissues and body organ functions. They can be classified as natural or synthetic. Polymethylmethacrylate (PMMA) is a synthetic biomaterial used, from the 1940’s to the present day, in orthopedic surgeries to replace joint surfaces and/or repair fractures. The basis of its components remains the same, small changes create variations in its properties; therefore, it is necessary to measure them. This work aims to characterize the thermal properties of PMMA, comparing them with those of soft tissues, bone and metallic prosthesis. The PMMA sample was stimulated 11 times for 3 seconds each by the modified transient plane source (MTPS), presenting the following averages: thermal conductivity =0.229± 0.006K(W/mK); effusivity =581.20± 6.22W$\mathrm{s}^{1/2}$/$\mathrm{m}^{2}$K and specific heat =1204.23± 6.88 J.kg. oC-1. The thermal properties obtained suggest that the cement would not cause local overheating, thus enabling the use of TUS on the region containing PMMA. The metallic prosthesis seems to play an important role in the dissipation of the heat generated, contributing to the non-heating of the multilayer system. However, more studies are needed to clarify this issue.