The effect of loading and material on the biomechanical properties and vitality of bovine cartilage in vitro.
2011 (English)In: Journal of Applied Biomaterials and Biomechanics, ISSN 1722-6899, Vol. 9, no 1, 47-53 p., 21445828Article in journal (Refereed) Published
PURPOSE: New methodology for long-term (270 h) biomechanical testing with living cartilage was developed. Polyurethane (PU) implant material was compared with stainless steel and reference samples in static unconfined compressive loading conditions on cartilage to provide a basis for dynamic testing of novel PU implant materials under conditions that simulate an articulating human knee joint.
METHODS: Custom-made tools and techniques were developed to prepare cylindrical samples from bovine patella with cartilage including subchondral bone. Specific incubator cups with static loading setups for a culture incubator were manufactured to keep bovine cartilage explants alive in cell culture conditions under unconfined static compressive loading (0.25 MPa) for 270 h (11.25 d). Four loading conditions of cartilage were studied: free (FREE), restrained minimal loading (RESTR), loading with a metal plate (MEW) and loading with polyurethane (PUW).
RESULTS: After static loading for 270 h, cartilage biomechanical tests indicated clear differences between the groups in frequency dependent dynamic stiffness curves. Surprisingly, the PU curves were closest to the FREE sample curves. Those with load and direct contact with metal (MEW) became significantly stiffer, while restrained samples became softer. Significant differences (p<0.05, Mann-Whitney's U test) in cell vitality between samples from various groups could be seen in fluorescein diacetate (FDA) and propidium iodide (PI) stained samples by confocal microscopic analysis. The approximate mean percentages of living cells after 270 hours cultivation were: FREE 87%, MEW 3%, PUW 35%, and RESTR 66%. Test results indicate that it is possible to keep cartilage cells alive in cell culture incubator conditions for two weeks period under a 0.25 MPa unconfined static loading. The FREE samples were most successful and cells loaded with PU were more vital than cells loaded with metal.
CONCLUSIONS: Based on the results, PU seems to be more compatible material than surgical steel in contact with living cartilage. Because of a large variation in the quality of bovine cartilage material from different animals, special care is necessary when selecting specimens to guarantee reliable and reproducible results.
Place, publisher, year, edition, pages
Wichtig Editore Srl, 2011. Vol. 9, no 1, 47-53 p., 21445828
Articular cartilage, Biomechanics, Mecahnical loading, Polyurethane, Viability
Orthopedics Biomaterials Science
Research subject Materials Science; Orthopaedics
IdentifiersURN: urn:nbn:se:umu:diva-104956DOI: 10.5301/JABB.2011.6472PubMedID: 21445828OAI: oai:DiVA.org:umu-104956DiVA: diva2:821933