HYDROXYAPATITE INFLUENCE ON THE THERMAL AND MECHANICAL PROPERTIES OF A HIGHLY POROUS BONE CEMENT

Abstract

Background: Bone cements based on acrylics have been used in different orthopedic procedures. Currently, the PMMA+HAp system is used as bone cement in a minimally invasive procedure known as Vertebroplasty. In this paper, the main goal was to study the Hydroxyapatite influence on the thermal and mechanical properties of a non-commercial bone cement. The relationship of the glass transition Tg with its mechanical properties of the samples was also investigated. Materials and Methods: The bone cement as (1-x)PMMA-xHAp binary system was prepared in six distinct concentration, such that [x] parameter is the concentration varying from 0.0 up to 0.5. The Hydroxyapatite (HAp) was synthesized using a sol-gel procedure following calcination by thermal treatment. The composite was prepared mixing Polymethylmethacrylate (PMMA) and HAp. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and mechanical compressive strength (CS) were used to study the thermal and mechanical properties. The DSC and TGA thermal profiles as a function to concentration [x] were presented. Results: The concentration at x = 0.5 or x5 exhibited mechanical behavior similar to porous tissues comparatively with bone. The CS lies in a range of 3.71 - 7.37 MPa and the glass transition temperature Tg = 103.01 ºC. Conclusions: There are direct relationships between the thermoplastic features of the PMMA+HAp system and its mechanical and thermal properties as a function of the biophosphonate concentrations ratio.