Manufacturing and characterization of plates for fracture fixation of bone with biocomposites of poly (lactic acid-co-glycolic acid) (PLGA) with calcium phosphates bioceramics

Abstract

Commercially, there are several plates and screws for bone fracture fixation made with PLA, however, its long degradation time and lack of integration with bone structure, provides interest in research using polymers with faster degradation, such as PLGA, and together with bioceramics, in order to improve bioactivity in bone regeneration. Based on this, in this study, bone fracture fixation plates composed of PLGA polymer matrix and combinations of 5 and 10%wt. of bioceramics were processed by microinjection. The bioceramics used comprehend nanostructured hydroxyapatite (n-HA), β-tricalcium phosphate (β-TCP) and calcium phosphate with ion substitution of magnesium (Mg-Ca/P) and strontium (Sr-Ca/P). The introduction of bioceramics modified thermal and mechanical properties of the polymer. The TGA analysis showed that there was a variation on the ceramic's mass inserted in relation to the expected values (5% and 10%wt.) in all groups of biocomposites. In general, Tg values obtained by DMA were slightly increased in almost all the biocomposites. The storage modulus (E') of biocomposites was higher for almost all groups of inserted ceramics, with exception of 5%n-HA. In the flexural tests, the biocomposites obtained a great dispersion in average values of fracture loading, presented lower values in relation to pure PLGA. There were difficulties in the processing of biocomposites with Mg-Ca/P and Sr-Ca/P, a factor that can be attributed to lack of homogeneity in the material mixing process. The results suggest modifications in thermal and mechanical properties of the PLGA plates with the bioceramics insertion and provide improvement understanding about of manufactured composites with PLGA and bioceramics.