Influence of particle size distribution on the rheological properties and mathematical model fitting of injectable borosilicate bioactive glass bone cement

Injectable bone cement combined with minimally invasive surgery has attracted much attention in recent years due to its rheological properties directly influencing its convenience and effectiveness in clinical applications. This study systematically investigates the influence of particle size distribution on the rheological, injectability, and anti-washout properties of borosilicate bioactive glass bone cement (BSBGC). Meanwhile, the setting time is also evaluated. Furthermore, a rheological model is proposed that describes the flow behaviour of BSBGC. Rheological results indicated that all the BSBGC samples exhibited non-Newtonian fluid behaviour, with thixotropic and shear-thinning properties. The BSBGC sample prepared via ball milling for 24 h (designated as CBM24) presented the largest thixotropic loop area, confirming that CBM24 has the greatest thixotropy. Particle size distribution greatly influenced the sol-gel time point, elastic and loss moduli, and viscosity of the BSBGC. Based on rheological results, four models (Ostwald–de Waele (Power law), Bingham, Herschel–Bulkley, and Casson) were selected and applied to fit the experimental data. It was found that the Power law and Herschel–Bulkley models were the most suitable for modelling the flow behaviour of the BSBGC, with the CBM24 sample having the greatest fitting proximity under the Power law model. Injectability test results showed that all BSBGC samples could be easily injected. Anti-washout test results indicated that CBM24 presented the most stable structure based on having the best anti-washout properties. Moreover, CBM24 had a reasonable initial and final setting time.