Using round α-TCP granules for improving CPC injectability

Abstract

Injectable biomaterials for minimal invasive surgery are gaining attention since they offer lower risks and shorter recovery times than regular procedures. Calcium phosphate cements (CPCs) stand out among injectable biomaterials focused on bone tissue repair due to their high bioactivity and setting in situ. Nevertheless, its poor injectability limits its clinical application. Aiming to improve CPCs injectability, this work proposes the study of spray-dried α-tricalcium phosphate granules as precursor of an apatite cement. α-TCP powders with two different particle sizes were used to optimize granulation and cement properties. Cement’s cohesion was increased maintaining the same physico-chemical properties of the control sample, i.e. cement obtained with no granulated powder. Moreover, with the same liquid-to-powder ratio, powder atomization was an efficient way to improve cement injectability. The reduction in the particle size did not interfere in granule morphology, but led to a cement with properties more suitable to clinical application. Combining particle size and spray-drying it was possible to obtain a cement with an injectability above 90%, a compression strength similar to cancellous bone and setting and cohesion times adequate to clinical application.