TY - JOUR
T1 - Micro-wear features on unique 100-Mrad cups
T2 - Two retrieved cups compared to hip simulator wear study
AU - Yamamoto, Kengo
AU - Masaoka, Toshinori
AU - Manaka, Masakazu
AU - Oonishi, Hironobu
AU - Clarke, Ian
AU - Shoji, Hiromu
AU - Kawanabe, Keiichi
AU - Imakiire, Atsuhiro
N1 - Funding Information:
This research was funded in part by the Foundation of the Western Center for Orthopaedic Research Foundation (Riverside, CA) and by the Dept of Orthopaedics at LLUMC. A grant from the Japanese Orthopaedic Research Society made possible the hip-simulator wear studies of ECL cups. The authors also acknowledge the support of the Analytical Electron Microscopy Facility (Dr. K. Bozhilov), at the University of California, Riverside.
PY - 2004/4
Y1 - 2004/4
N2 - We studied the micro-wear phenomena of unique, extensively cross-linked polyethylene cups (cross-linked with 1,000 kGy-irradiation) that had been used briefly in Japan. Two retrievals (at 15 years) came from the Japanese "SOM" hip system (implanted 1971-78). These were compared to a set of 0kGy and 500-1,500 kGy cups run in our hip simulator. The polyethylene cups that had not been cross-linked had the greatest wear. The worn areas had a burnished appearance and were clearly separated from the unworn region by a distinct ridge-line. The worn areas had lost all machine tracks, showed a large amount of UHMWPE 'flow', and long PE fibrils. The associated surface rippling was degraded. These features were considered synonymous with severe polyethylene wear. In contrast, the worn areas in the very cross-linked cups had a visibly matte surface and no ridge-line. Micro-examination showed that the machine tracks were still present Ripple formations were less obvious than in the cups that were not cross-linked, polyethylene surface fibrils were scarcer and all the fibrils were much smaller than in the cups that were not crosslinked. Our two retrieved cups and the simulator cups confirmed the greater wear-resistance of very cross-linked polyethylene. It should also be noted that the SOM cup design and processing were unique and differed greatly from that of modern polyethylene cups.
AB - We studied the micro-wear phenomena of unique, extensively cross-linked polyethylene cups (cross-linked with 1,000 kGy-irradiation) that had been used briefly in Japan. Two retrievals (at 15 years) came from the Japanese "SOM" hip system (implanted 1971-78). These were compared to a set of 0kGy and 500-1,500 kGy cups run in our hip simulator. The polyethylene cups that had not been cross-linked had the greatest wear. The worn areas had a burnished appearance and were clearly separated from the unworn region by a distinct ridge-line. The worn areas had lost all machine tracks, showed a large amount of UHMWPE 'flow', and long PE fibrils. The associated surface rippling was degraded. These features were considered synonymous with severe polyethylene wear. In contrast, the worn areas in the very cross-linked cups had a visibly matte surface and no ridge-line. Micro-examination showed that the machine tracks were still present Ripple formations were less obvious than in the cups that were not cross-linked, polyethylene surface fibrils were scarcer and all the fibrils were much smaller than in the cups that were not crosslinked. Our two retrieved cups and the simulator cups confirmed the greater wear-resistance of very cross-linked polyethylene. It should also be noted that the SOM cup design and processing were unique and differed greatly from that of modern polyethylene cups.
UR - http://www.scopus.com/inward/record.url?scp=2342653568&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=2342653568&partnerID=8YFLogxK
U2 - 10.1080/00016470412331294375
DO - 10.1080/00016470412331294375
M3 - Article
C2 - 15180227
SN - 0001-6470
VL - 75
SP - 134
EP - 141
JO - Acta Orthopaedica Scandinavica
JF - Acta Orthopaedica Scandinavica
IS - 2
ER -