Quaternised chitosan-loaded polymethylmethacrylate bone cement: Biomechanical and histological evaluations

Abstract

Our previous studies have demonstrated that the quaternised chitosan-loaded polymethylmethacrylate (PMMA) is a promising new antibacterial bone cement. The aim of this study was to evaluate biomechanical properties of quaternised chitosan-loaded PMMA in vitro and interface histology between cement and bone in vivo. In this study, hydroxypropyltrimethyl ammonium chloride chitosan (HACC) with 26% degree of substitution (referred to as 26% HACC) was loaded into PMMA bone cement at a 20% mass ratio, and the specimens of 26% HACC-loaded PMMA bone cement (PMMA–H) were prepared for compressive and bending mechanical test according to ISO 5883-2002 standard prior to and after the 4-week immersion in PBS. The chitosan-loaded PMMA bone cement (PMMA–C) at the same mass ratio, pure PMMA, and gentamicin-loaded PMMA (PMMA–G) were also prepared and tested as controls. Then each of four kinds of bone cements was implanted into the rabbit femoral condyle and the osseointegration of the cement–bone interface was evaluated after its implantation over 6 weeks. The results show that biomechanical properties of both PMMA–C and PMMA–H were reduced significantly compared with the PMMA or PMMA–C, and the elastic modulus of PMMA–H was close to that of human cancellous bone. Histological observation in animal studies indicates that there was better osseointegration at the cement–bone interface in the PMMA–H group than that in the PMMA, PMMA–G, or PMMA–C groups. More new bone formation was found around PMMA–H bone cement as compared with that in the other three groups. Our findings indicated that the biomechanical properties of PMMA–H were reduced but close to that of neighbouring bone. The PMMA–H had good biocompatibility and osseointegration potential, implying its suitability for vertebral augmentation of osteoporotic vertebral compression fractures and fixation of prosthesis in cemented joint replacement.