title: Enhanced mechanical properties of a novel, injectable, fiber-reinforced brushite cement.
abstract: Injectable, brushite-forming calcium phosphate cements (CPCs) have great potential as bone replacement materials due to enhanced degradability and long-term inclusion in bone remodeling. However, the use of such brushite-forming CPCs in load-bearing areas is limited by their low mechanical strength. One approach to overcome this limitation is the use of reinforcing fibers. Thus, an injectable, biodegradable, brushite-forming CPC based on beta-tricalcium phosphate/phosphoric acid with fiber reinforcement was developed for minimally invasive surgery. The fibers (diameter 25 µm; length 0.25, 1 or 2mm) were extruded from poly(l-lactide-co-glycolide) acid (PLGA) and added to the CPC (2.5, 5 or 7.5% (w/w)). Independent of the fiber content, injectability of the CPC was retained up to a fiber length of 1mm. The addition of all PLGA fiber types increased diametral tensile strength, biaxial flexural strength, and flexural strength by up to 25% (p ≤ 0.05 for the diametral tensile strength for the CPC with 5% (w/w) 1mm fibers and the biaxial flexural strength of the CPC with 5% (w/w) 0.25 mm fibers). In contrast, the work of fracture strongly and significantly increased (p<0.01) by up to 12.5-fold. At constant fiber content, the mechanical properties of the fiber-reinforced CPC were mostly augmented with increasing fiber length. Also, the addition of PLGA fibers to the brushite-forming CPC (up to 7.5% (w/w)) only transiently delayed cell growth and did not decrease cell viability. Fiber reinforcement of CPCs thus augments their mechanical strength while preserving the injectability and biocompatibility required for their application in modern surgery.
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich-Schiller-University Jena, Jena, Germany; Jena School for Microbial Communication (JSMC), Friedrich-Schiller-University Jena, Jena, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Maenz
authors.affiliation: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Waldkrankenhaus "Rudolf Elle," Eisenberg, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Kunisch
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich-Schiller-University Jena, Jena, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Mühlstädt
authors.affiliation: Thuringian Institute of Textile and Plastics Research, Rudolstadt, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Böhm
authors.affiliation: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Waldkrankenhaus "Rudolf Elle," Eisenberg, Germany.
authors.forename: Victoria
authors.initials: V
authors.lastname: Kopsch
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich-Schiller-University Jena, Jena, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Bossert
authors.affiliation: Experimental Rheumatology Unit, Department of Orthopedics, Jena University Hospital, Waldkrankenhaus "Rudolf Elle," Eisenberg, Germany.
authors.forename: Raimund W
authors.initials: RW
authors.lastname: Kinne
authors.affiliation: Chair of Materials Science, Otto Schott Institute of Materials Research, Friedrich-Schiller-University Jena, Jena, Germany; Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Jena, Germany; Jena School for Microbial Communication (JSMC), Friedrich-Schiller-University Jena, Jena, Germany. Electronic address: k.jandt@uni-jena.de.
authors.forename: Klaus D
authors.initials: KD
authors.lastname: Jandt
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001843:Bone Cements / Q000737:chemistry*; D018786:Bone Substitutes; D002130:Calcium Phosphates / Q000737:chemistry*; D049109:Cell Proliferation; D002470:Cell Survival; D055119:Elastic Modulus; D019344:Lactic Acid / Q000737:chemistry*; D008422:Materials Testing; D051379:Mice; D019060:Minimally Invasive Surgical Procedures; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011208:Powders; D013314:Stress, Mechanical; D013718:Tensile Strength; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D001843:Bone Cements; D018786:Bone Substitutes; D002130:Calcium Phosphates; D011208:Powders; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C020243:calcium phosphate; C494366:calcium phosphate, dibasic, dihydrate
keywords: Biocompatibility; Calcium phosphate cement; Fiber reinforcement; Injectability; Mechanical properties