Wear pattern on a retrieved Total Knee Replacement: The “fourth body abrasion”

Fourth body abrasion of the PE insert in a knee implant: Coating bead loosening and entrapment in the articulating interface (A), Third body abrasion of the PE insert: large scratches (B), Fourth body generation by abrasion of the coating beads embedded in the PE insert (C), Fourth body abrasion of the PE insert: smaller scratches (D).79