The stability mechanisms of an injectable calcium phosphate ceramic suspension

  • Ahmed Fatimi
  • Jean-François Tassin
  • Monique A. V. Axelos
  • Pierre Weiss


Calcium phosphate ceramics are widely used as bone substitutes in dentistry and orthopedic applications. For minimally invasive surgery an injectable calcium phosphate ceramic suspension (ICPCS) was developed. It consists in a biopolymer (hydroxypropylmethylcellulose: HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP) as fillers. The stability of the suspension is essential to this generation of “ready to use” injectable biomaterial. But, during storage, the particles settle down. The engineering sciences have long been interested in models describing the settling (or sedimentation) of particles in viscous fluids. Our work is dedicated to the comprehension of the effect of the formulation on the stability of calcium phosphate suspension before and after steam sterilization. The rheological characterization revealed the macromolecular behavior of the suspending medium. The investigations of settling kinetics showed the influence of the BCP particle size and the HPMC concentration on the settling velocity and sediment compactness before and after sterilization. To decrease the sedimentation process, the granule size has to be smaller and the polymer concentration has to increase. A much lower sedimentation velocity, as compared to Stokes law, is observed and interpreted in terms of interactions between the polymer network in solution and the particles. This experimentation highlights the granules spacer property of hydrophilic macromolecules that is a key issue for interconnection control, one of the better ways to improve osteoconduction and bioactivity.


Calcium Phosphate Sedimentation Velocity Biphasic Calcium Phosphate Sediment Volume Newtonian Viscosity 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



This present work was supported by the regional program BIOREGOS (Région Pays de la Loire, France). The help of Paul Pilet (LIOAD INSERM U791, Nantes) for the SEM analysis, Jean-Michel Bouler (LIOAD INSERM U791, Nantes) for BCP preparation, and Stephane Grolleau (CNRS IMN, Nantes) for density measurements is acknowledged with gratitude. We thank Colorcon® for providing the Methocel™ E4M.


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Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Ahmed Fatimi
    • 1
    • 2
  • Jean-François Tassin
    • 3
  • Monique A. V. Axelos
    • 4
  • Pierre Weiss
    • 1
    • 2
  1. 1.Laboratoire d’Ingénierie Ostéo-Articulaire et Dentaire (LIOAD), INSERM U791Nantes Cedex 1France
  2. 2.Laboratoire d’Ingénierie Ostéo-Articulaire et Dentaire (LIOAD), Université de NantesNantes Cedex 1France
  3. 3.Laboratoire Polymères, Colloïdes, Interfaces (LPCI), UMR 6120CNRS, Université du MaineLe Mans Cedex 9France
  4. 4.INRA, UR1268 Biopolymères Interactions Assemblages (BIA)Nantes Cedex 3France

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