Lopez-Heredia M.A. - Influence of the pore generator on the evolution of the mechanical properties and the porosity and interconnectivity of a calcium phosphate cement

Marco A. Lopez-Heredia a, Kemal Sariibrahimoglu a,1, Wanxun Yang a,1, Marc Bohner b, Daiki Yamashita c,
Aliz Kunstar d, Aart A. van Apeldoorn d, Ewald M. Bronkhorst e, Rosa P. Félix Lanao a, Sander C.G. Leeuwenburgh a, Kiyoshi Itatani c, Fang Yang a, Phil Salmon f, Joop G.C. Wolke a, John A. Jansen a,⇑

Acta Biomaterialia 2011

Abstract

Porosity and interconnectivity are important properties of calcium phosphate cements (CPCs) and bonereplacement
materials. Porosity of CPCs can be achieved by adding polymeric biodegradable pore-generating
particles (porogens), which can add porosity to the CPC and can also be used as a drug-delivery system.
Porosity affects the mechanical properties of CPCs, and hence is of relevance for clinical application
of these cements. The current study focused on the effect of combinations of polymeric mesoporous porogens
on the properties of a CPC, such as specific surface area, porosity and interconnectivity and the
development of mechanical properties. CPC powder was mixed with different amounts of PLGA porogens
of various molecular weights and porogen sizes. The major factors affecting the properties of the CPC
were related to the amount of porogen loaded and the porogen size; the molecular weight did not show
a significant effect per se. A minimal porogen size of 40 lm in 30 wt.% seems to produce a CPC with
mechanical properties, porosity and interconnectivity suitable for clinical applications. The properties
studied here, and induced by the porogen and CPC, can be used as a guide to evoke a specific hostresponse
to maintain CPC integrity and to generate an explicit bone ingrowth.