title: Biodegradable Fe-based alloys for use in osteosynthesis: outcome of an in vivo study after 52 weeks.
abstract: This study investigates the degradation performance of three Fe-based materials in a growing rat skeleton over a period of 1 year. Pins of pure Fe and two Fe-based alloys (Fe-10 Mn-1Pd and Fe-21 Mn-0.7C-1Pd, in wt.%) were implanted transcortically into the femur of 38 Sprague-Dawley rats and inspected after 4, 12, 24 and 52 weeks. The assessment was performed by ex vivo microfocus computed tomography, weight-loss determination, surface analysis of the explanted pins and histological examination. The materials investigated showed signs of degradation; however, the degradation proceeded rather slowly and no significant differences between the materials were detected. We discuss these unexpected findings on the basis of fundamental considerations regarding iron corrosion. Dense layers of degradation products were formed on the implants' surfaces, and act as barriers against oxygen transport. For the degradation of iron, however, the presence of oxygen is an indispensable prerequisite. Its availability is generally a critical factor in bony tissue and rather limited there, i.e. in the vicinity of our implants. Because of the relatively slow degradation of both pure Fe and the Fe-based alloys, their suitability for bulk temporary implants such as those in osteosynthesis applications appears questionable.
authors.affiliation: Department of Paediatric Orthopaedics, Medical University Graz, 8036 Graz, Austria.
authors.forename: Tanja
authors.initials: T
authors.lastname: Kraus
authors.affiliation: Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Frank
authors.initials: F
authors.lastname: Moszner
authors.affiliation: Department of Orthopaedics, Medical University Graz, 8036 Graz, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Fischerauer
authors.affiliation: Department of Orthopaedics, Medical University Graz, 8036 Graz, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Fiedler
authors.affiliation: Department of Orthopaedics, Medical University Graz, 8036 Graz, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Martinelli
authors.affiliation: Department of Orthopaedics, Medical University Graz, 8036 Graz, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Eichler
authors.affiliation: Julius Wolff Institut, Charité-Universitätsmedizin Berlin, Augustenburgerplatz 1, 13353 Berlin, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Witte
authors.affiliation: Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover, Germany.
authors.forename: Elmar
authors.initials: E
authors.lastname: Willbold
authors.affiliation: Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Schinhammer
authors.affiliation: University of Natural Resources and Life Sciences (BOKU), Peter-Jordan Strasse 82, A-1190 Vienna, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Meischel
authors.affiliation: Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Uggowitzer
authors.affiliation: Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
authors.forename: Jörg F
authors.initials: JF
authors.lastname: Löffler
authors.affiliation: Department of Orthopaedics, Medical University Graz, 8036 Graz, Austria. Electronic address: annelie.weinberg@t-online.de.
authors.forename: Annelie
authors.initials: A
authors.lastname: Weinberg
mesh_terms: D000497:Alloys; D000818:Animals; D001672:Biocompatible Materials; D007501:Iron / Q000737:chemistry*; D008297:Male; D008855:Microscopy, Electron, Scanning; D010012:Osteogenesis; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D007501:Iron
keywords: Biodegradation; Fracture fixation; Iron; Iron alloys; μCT