Physical-chemical characterization of PMMA-based hip implant centralizer and spacer: evaluation of monomers and impurities screening

The present work proposes a complete set of experiments for chemical characterization of PMMA-based hip implant centralizers and spacers screening. Evaluation of chemical structure, including screening for residual monomer and other impurities from manufacturing process, was performed. Data from FTIR and NMR confirmed chemical structure while results from NMR and DSC allowed the determination of polymer tacticity, in which results exhibit syndiotactic and atactic segments as well as a minor proportion of isotactic segments. Gel permeation chromatography showed a trimodal distribution, the first spectrum peak exhibits a molar mass (Mn) close to 42,000 Da, an average molar mass (Mw) close to 81,000 Da, and a Z molar mass close to 140,000 Da for all samples, although with a dispersion degree close to two (02). It was also observed by GPC analysis of another two populations with a low molecular weight with low-intensity peaks. GPC-UV analysis also showed the presence of benzoyl peroxide (BPO) in the polymeric structure. Results demonstrated the presence of residual monomers in concentrations ranging from 2.27 to 5.79% of the polymeric mass. Centralizers and spacers presented similar results, except for residual monomer in which the centralizers presented a higher concentration.

Automated summary

This study proposes a complete experimental plan for the chemical characterization of PMMA-based hip implant centralizers and spacers. The results show the presence of residual monomers with concentrations ranging from 2.27% to 5.79% in these products, and benzoyl peroxide (BPO) was detected in the polymeric structure. The combined results from various analytical techniques demonstrate differences in chemical structure and molecular weight distribution of these products.