title: The effect on wear of lift-off in total knee arthroplasty.
abstract: Femoral lift-off has been reported in total knee arthroplasty using dynamic fluoroscopic analysis. However, the effect of femoral lift-off on ultra-high-molecular-weight polyethylene (UHMWPE) is not clear. The objective of this study was to evaluate the effect of lift-off movement on the wear of UHMWPE using a pin-on-disc testing machine. Using oxidised UHMWPE, delamination was observed in 70% of the discs with lift-off movement, as against none in without lift-off movement (p=0.0603). In non-oxidised UHMWPE the depth of the wear track was increased in the impact area after lift-off, but there was no delamination and no increase in wear as measured by weight loss. UHMWPE can sustain the impact of after lift-off with neither delamination nor wear by other mechanisms. In contrast, degraded (i.e., oxidised) UHMWPE undergoes delamination after lift-off. Since it is probable that lift-off cannot be prevented, oxidised UHMWPE should never be used in TKA.
authors.affiliation: Yasaka-cho Kokuho Hospital, Kyoto, Japan. todos@fb3.so-net.ne.jp
authors.forename: Shinichi
authors.initials: S
authors.lastname: Todo
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Blunn
authors.forename: Mark
authors.initials: M
authors.lastname: Harrison
authors.forename: Michael A R
authors.initials: MA
authors.lastname: Freeman
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D019245:Compressive Strength; D019544:Equipment Failure Analysis / Q000379:methods*; D017276:Friction; D006801:Humans; D007593:Joint Instability / Q000209:etiology / Q000503:physiopathology; D007720:Knee Prosthesis; D008422:Materials Testing / Q000379:methods*; D010084:Oxidation-Reduction; D011095:Polyethylenes / Q000737:chemistry* / Q000145:classification; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D016474:Weight-Bearing
chemical_list: D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene