Analysis and evaluation of a biomedical polycarbonate urethane tested in an in vitro study and an ovine arthroplasty model. Part II: in vivo investigation.
The polyurethane (PU) elastomer Corethane 80A (Corvita) is being considered as the acetabular bearing material in a novel total replacement hip joint. Its biostability was investigated in vitro (Analysis and evaluation of a biomedical polycarbonate urethane tested in an in vitro study and an ovine arthroplasty model. Part I: material selection and evaluation, Biomaterials, in press) together with three other commercially available biomedical PUs: Pellethane 2363-80A (DOW Chemical), a polyhexamethylene oxide based PU, PHMO-PU (CSIRO, not supplied as a commercial product) and ChronoFlex AL-80A (CardioTech). From the in vitro studies, Corethane 80A displayed the best overall resistance to hydrolysis, ESC, MIO and calcification, followed by ChronoFlex 80A and PHMO-PU, with Pellethane 80A being the least stable. Building on the in vitro investigation, the follow-up in vivo study (reported here) assessed Corethane 80A as the bearing layer in a prototype compliant layer acetabular cup, in a fully functioning ovine total hip arthoplasty (THA) model. PU degradation in the retrieved cups was analysed using a range of analytical and physical-testing methods including mechanical testing, differential scanning calorimetry, Fourier transform infrared spectroscopy and environmental scanning electron microscopy. The Corethane 80A functioned well in the THA model, with the bearing surfaces of the retrieved hip cups showing no significant evidence of biodegradation or wear damage after 3 years in vivo. The findings in this study provide compelling evidence for the biostability and effectiveness of acetabular cups incorporating a Corethane 80A compliant bearing layer.
Department of Materials Science and Metallurgy, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3QZ, UK.
Imran
I
Khan
Nigel
N
Smith
Eric
E
Jones
Dudley S
DS
Finch
Ruth Elizabeth
RE
Cameron
D015502:Absorptiometry, Photon; D000077:Acetabulum / Q000473:pathology / Q000601:surgery; D000818:Animals; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D001672:Biocompatible Materials / Q000737:chemistry*; D001673:Biodegradation, Environmental; D004868:Equipment Failure; D006868:Hydrolysis; D008297:Male; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000032:analysis; D008970:Molecular Weight; D010014:Osteolysis / Q000209:etiology; D010084:Oxidation-Reduction; D011076:Polycarboxylate Cement / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry*; D019736:Prostheses and Implants / Q000009:adverse effects; D012756:Sheep; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013499:Surface Properties
D001672:Biocompatible Materials; D008903:Minerals; D011076:Polycarboxylate Cement; D011140:Polyurethanes; C094863:corethane 80A; C059617:pellethane 2363-55D; C005506:polycarbonate; C090631:polyhexamethylene oxide