Optimizing percolation and injectability behavior of highly filled β-tricalcium phosphate suspensions

In recent years, calcium phosphate cements have been widely used in bone repair and treatment. The development of percutaneous surgical methods has been interested in the study of the injection behavior of calcium phosphate cements. The aim of this study was to examine the factors affecting the experiment using percolation (liquid phase separation) and injectability (pressure adaptive flow stability) behaviors of highly filled β-Tricalcium phosphate suspensions), using capillary flow process parameters, Hydroxyethyl cellulose (HEC) and Polyethylene Glycol (PEG-400) additives which depicts the effects of factorial design. According to the injectability and percolation responses, the suitability of the model was confirmed by the residual value results. The prepared suspensions were characterized by capillary and low-oscillation rheometers. The flow behavior of the β-TCP suspension was examined in detail. HEC additive weight percentage is determined as 2 wt.%, has been identified as the parameter that most positively affects the highly filled β-TCP suspension as rheological features). In addition, when the injection rate was 15 mm/min, and the nozzle diameter and length ratio was 15 that was injected successfully with a rate of 99.21% and the percolation (%) value was found to be the lowest as 0.82. 10 mg/ml PEG-400 in 2 wt.% HEC provided a lubricative effect, significantly reducing the injection force. Capillary rheometry force-displacement graphs were examined according to each process and add-on parameter, and suspensions containing 2% HEC by weight generally showed stable flow behavior. Significant percolation was observed in suspensions where the liquid phase add-ons were less than this range and the interaction graphs and experimental design results showed it. As a result of capillary rheometry, the n parameter defined for the force law power law was the HEC-doped suspension with the highest percentage of weight determined as 2 wt.% and was 0.515. The lowest n parameter was observed in aqueous suspension and calculated as 0.133.