title: Influence of polymeric additives on the cohesion and mechanical properties of calcium phosphate cements.
abstract: To expand the clinical applicability of calcium phosphate cements (CPCs) to load-bearing anatomical sites, the mechanical and setting properties of CPCs need to be improved. Specifically, organic additives need to be developed that can overcome the disintegration and brittleness of CPCs. Hence, we compared two conventional polymeric additives (i.e. carboxylmethylcellulose (CMC) and hyaluronan (HA)) with a novel organic additive that was designed to bind to calcium phosphate, i.e. hyaluronan-bisphosphonate (HABP). The unmodified cement used in this study consisted of a powder phase of α-tricalcium phosphate (α-TCP) and liquid phase of 4% NaH2PO4·2H2O, while the modified cements were fabricated by adding 0.75 or 1.5 wt% of the polymeric additive to the cement. The cohesion of α-TCP was improved considerably by the addition of CMC and HABP. None of the additives improved the compression and bending strength of the cements, but the addition of 0.75% HABP resulted into a significantly increased cement toughness as compared to the other experimental groups. The stimulatory effects of HABP on the cohesion and toughness of the cements is hypothesized to derive from the strong affinity between the polymer-grafted bisphosphonate ligands and the calcium ions in the cement matrix.
authors.affiliation: Department of Biomaterials, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Jie
authors.initials: J
authors.lastname: An
authors.affiliation: Department of Biomaterials, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Joop G C
authors.initials: JG
authors.lastname: Wolke
authors.affiliation: Department of Biomaterials, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: John A
authors.initials: JA
authors.lastname: Jansen
authors.affiliation: Department of Biomaterials, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands. Sander.Leeuwenburgh@radboudumc.nl.
authors.forename: Sander C G
authors.initials: SC
authors.lastname: Leeuwenburgh
mesh_terms: D001843:Bone Cements / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D002266:Carboxymethylcellulose Sodium / Q000737:chemistry*; D006820:Hyaluronic Acid / Q000737:chemistry*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D013314:Stress, Mechanical; D014961:X-Ray Diffraction
chemical_list: D001843:Bone Cements; D002130:Calcium Phosphates; D010710:Phosphates; D011108:Polymers; C485828:alpha-tricalcium phosphate; D006820:Hyaluronic Acid; C020243:calcium phosphate; D002266:Carboxymethylcellulose Sodium; C018279:sodium phosphate