Wear mode and wear mechanism of retrieved acetabular cups.
Nineteen ultra-high-molecular-weighted polyethylene (UHMWPE) cups were retrieved at revision surgery. The implant period was on average 9.9 (0.25-20.7) years. The cups were classified into the high-wear group (wear rate above 140 mm(3)/year), intermediate-wear group (wear rate 80-140 mm(3)/year) and low-wear group (wear rate below 80 mm(3)/year). The wear rate was measured by a fluid displacement method. The cups were studied using scanning electron microscopy. Ripples mainly appeared on the cups in the low-wear group, and nodules and fibrils mainly appeared in the high-wear group. Folding was observed in all cups, but folding with numerous fibrils was conspicuous in the high-wear group. The cup retrieved at 3 months already exhibited folding. From these results, the wear response appeared to be a three-step process: (1) foldings are generated, (2) ripples are formed on the surface, and (3) fibrils are produced from the surface and delaminated, leading to the formation of wear debris.
Yamamoto
Kengo
K
Department of Orthopaedic Surgery, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, 160-0023 Tokyo, Japan. kengo-y@tkg.att.ne.jp
Imakiire
Atsuhiro
A
Masaoka
Toshinori
T
Shishido
Takaaki
T
Mizoue
Tatsuro
T
Clarke
Ian C
IC
Shoji
Hiromu
H
Kawanabe
Keiichi
K
Tamura
Jiro
J
D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation; D001672:Biocompatible Materials / Q000009:adverse effects*; D020878:Device Removal; D019544:Equipment Failure Analysis / Q000379:methods; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D020959:Polyethylene / Q000009:adverse effects*; D011475:Prosthesis Failure; D012086:Reoperation
D001672:Biocompatible Materials; D020959:Polyethylene