title: Wear of congruent meniscal bearings in unicompartmental knee arthroplasty: a retrieval study of 16 specimens.
abstract: Many designs of unicompartmental knee replacement show early and mid-term failure due to polyethylene wear. We studied the wear rate of congruent polyethylene meniscal bearings retrieved from failed Oxford unicompartmental knee replacements. We examined 16 bearings, 0.8 to 12.8 years after implantation, measuring their thickness and comparing it with that of 14 unused bearings. The mean rate of penetration, which included the effects of wear at both upper and lower surfaces, was 0.036 mm per year (maximum 0.08). Bearings as thin as 3.5 mm wore no faster than thicker models, but ten with evidence of impingement had greater wear. The six bearings with no impingement showed a mean rate of penetration of 0.01 mm per year. In unicompartmental knee replacement, careful implantation of fully congruous meniscal bearings can avoid failure due to polyethylene wear.
authors.affiliation: Nuffield Orthopaedic Centre, Oxford, England.
authors.forename: V
authors.initials: V
authors.lastname: Psychoyios
authors.forename: R W
authors.initials: RW
authors.lastname: Crawford
authors.forename: J J
authors.initials: JJ
authors.lastname: O'Connor
authors.forename: D W
authors.initials: DW
authors.lastname: Murray
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects; D008592:Menisci, Tibial; D008875:Middle Aged; D011095:Polyethylenes; D011475:Prosthesis Failure; D013997:Time Factors
chemical_list: D011095:Polyethylenes