title: Tribological and mechanical performance evaluation of metal prosthesis components manufactured via metal injection molding.
abstract: The increasing number of total joint replacements, in particular for the knee joint, has a growing impact on the healthcare system costs. New cost-saving manufacturing technologies are being explored nowadays. Metal injection molding (MIM) has already demonstrated its suitability for the production of CoCrMo alloy tibial trays, with a significant reduction in production costs, by holding both corrosion resistance and biocompatibility. In this work, mechanical and tribological properties were evaluated on tibial trays obtained via MIM and conventional investment casting. Surface hardness and wear properties were evaluated through Vickers hardness, scratch and pin on disk tests. The MIM and cast finished tibial trays were then subjected to a fatigue test campaign in order to obtain their fatigue load limit at 5 millions cycles following ISO 14879-1 directions. CoCrMo cast alloy exhibited 514 HV hardness compared to 335 HV of MIM alloy, furthermore it developed narrower scratches with a higher tendency towards microploughing than microcutting, in comparison to MIM CoCrMo. The observed fatigue limits were (1,766 ± 52) N for cast tibial trays and (1,625 ± 44) N for MIM ones. Fracture morphologies pointed out to a more brittle behavior of MIM microstructure. These aspects were attributed to the absence of a fine toughening and surface hardening carbide dispersion in MIM grains. Nevertheless, MIM tibial trays exhibited a fatigue limit far beyond the 900 N of maximum load prescribed by ISO and ASTM standards for the clinical application of these devices.
authors.affiliation: Department of Chemistry, Materials, and Chemical Engineering "G. Natta", Politecnico Di Milano, Piazza L. Da Vinci 32, 20133, Milan, Italy.
authors.forename: Virginia
authors.initials: V
authors.lastname: Melli
authors.forename: Mateusz
authors.initials: M
authors.lastname: Juszczyk
authors.forename: Enrico
authors.initials: E
authors.lastname: Sandrini
authors.forename: Giovanni
authors.initials: G
authors.lastname: Bolelli
authors.forename: Benedetta
authors.initials: B
authors.lastname: Bonferroni
authors.forename: Luca
authors.initials: L
authors.lastname: Lusvarghi
authors.forename: Alberto
authors.initials: A
authors.lastname: Cigada
authors.forename: Tiziano
authors.initials: T
authors.lastname: Manfredini
authors.forename: Luigi
authors.initials: L
authors.lastname: De Nardo
mesh_terms: D001672:Biocompatible Materials; D006801:Humans; D007595:Joint Prosthesis; D008670:Metals / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D011474:Prosthesis Design
chemical_list: D001672:Biocompatible Materials; D008670:Metals