Design & development of a novel glass polyalkenoate cement for sternal fixation and repair, in the event of median sternotomy surgery

Median sternotomy surgery is the gold standard for cardiac/thoracic procedures such as open-heart surgery. With over one million median sternotomy surgeries performed worldwide every year, sternal wound complications pose a serious risk to the health of affected patients. Various techniques have been used for sternal fixation including wiring, plate-screw systems and cementing. The ideal sternal closure device is the one which has mechanical properties suited to the local environment, biocompatibility, radio-opacity, cost-effectiveness and ease of removal when necessary. None of the techniques that have been utilized for sternal fixation to date address all of these requirements. Glass polyalkenoate cements (GPCs) have a long history of use in restorative and orthodontic dentistry and ear, nose and throat (ENT) surgery but have yet to be indicated for musculoskeletal applications. This dissertation relates to the development of new GPC-based adhesives for use in sternal closure. A series of novel glasses based on the system 48SiO2-(36-X) ZnO-6CaO-8SrO-2P2O5-XTa2O5 with X varying from 0.0 to 8.0 mole percentage were fabricated and characterized. The structural features as a function of Ta2O5 content were investigated by network connectivity (NC) calculations, x-ray diffraction (XRD), particle size analysis (PSA), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and magic angle spinning-nuclear magnetic resonance (MAS-NMR). The thermal properties of the glasses were obtained by performing simultaneous thermal analysis (STA). The effect of glass structure on pH and solubility was also evaluated. The formulated glasses were used to prepare GPC adhesive materials and tested for their suitability for sternal fixation. The data collected has confirmed that substituting up to 0.5 mole percentage of ZnO with Ta2O5 in the glass system under study resulted in the formation of adhesives that are deemed suitable for sternal fixation. The formulated cements, based on the use of glasses containing no greater than 0.5 mole percentage of Ta2O5 have rheology, strength, radiopacity, antibacterial and in-vitro behavior suitable for sternal fixation. To the best knowledge of the candidate, this dissertation is the first to report the use of tantalum-containing GPC-based adhesives for sternal closure. Based on the obtained results, the formulated adhesives can be used in conjunction with sternal cable ties (current standard method) to offer optimal fixation for patients and reduce post-operative complications such as bacterial infection and pain from micro-motion.