Analysis of wear in retrieved mobile and fixed bearing knee inserts.
One purported advantage for mobile bearing (MB) knee implants is reduced polyethylene wear. Twenty-three retrieved Low Contact Stress (LCS) MB and 31 Anatomic Modular Knee (AMK) fixed bearing tibial polyethylene inserts, both Enduron (Depuy, Warsaw, IN) and sterilized by gas plasma, were graded for top and backside wear using the Hood grading system. For articular surface wear, there was no statistical difference between pitting and scratching, but burnishing was twice as much for MB inserts (P = .003). For backside scores, there was a minimal amount of pitting for both, but the scratching score was twice (P = .000) and the burnishing score was 3 times greater for MB inserts (P = .000). At more than 5 years in situ, the linear wear measurements were similar for the 2 groups (mean penetration was 0.329 mm for MB and 0.320 mm for fixed bearing).
Engh
Gerard A
GA
Anderson Orthopaedic Research Institute, Alexandria, Virginia 22306, USA.
Zimmerman
Rebecca L
RL
Parks
Nancy L
NL
Engh
C Anderson
CA
D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D020878:Device Removal; D019544:Equipment Failure Analysis / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology / Q000601:surgery; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology
D020959:Polyethylene