Tibial high-density polyethylene wear in conforming tibiofemoral prostheses.
We have studied 27 tibial prostheses retrieved from knee replacements after 1 to 9 years. In 22 the femoral components were of cobalt-chrome, in five polyacetal. The design of the components gave a nominal contact area of 320 mm2 on each condyle. The tibial component was of high-density polyethylene (HDP) at least 6 mm thick, and not heat-treated. In the metal/HDP prostheses the average wear rate was 0.025 mm/year. The relative wear on the medial and lateral sides was related to the leg axis. None of the retrieved prostheses showed any severe disruption of their surface. The polyacetal/HDP prostheses showed similar wear with a statistically insignificant trend towards slower penetration. We conclude that the rate of wear of HDP in a conforming tibiofemoral bearing with a fixed tibial component at least 6 mm thick and not heat-treated is slow enough to be safe in clinical practice.
Plante-Bordeneuve
P
P
Orthopaedic Department, Royal London Hospital Medical College, UK.
Freeman
M A
MA
D000080:Acetals; D000368:Aged; D001696:Biomechanical Phenomena; D002858:Chromium Alloys; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery; D007720:Knee Prosthesis / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011095:Polyethylenes; D011108:Polymers; D011474:Prosthesis Design / Q000706:statistics & numerical data; D011475:Prosthesis Failure; D013499:Surface Properties; D013977:Tibia; D013997:Time Factors
D000080:Acetals; D002858:Chromium Alloys; D011095:Polyethylenes; D011108:Polymers; C016067:polyacetal