Highly crosslinked polyethylene does not reduce aseptic loosening in cemented THA 10-year findings of a randomized study.
BACKGROUND
Polyethylene (PE) wear particles are believed to cause aseptic loosening and thereby impair function in hip arthroplasty. Highly crosslinked polyethylene (XLPE) has low short- and medium-term wear rates. However, the long-term wear characteristics are unknown and it is unclear whether reduced wear particle burden improves function and survival of cemented hip arthroplasty.


OBJECTIVE
We asked whether XLPE wear rates remain low up to 10 years and whether this leads to improved implant fixation, periprosthetic bone quality, and clinical function compared to conventional PE.


METHODS
We randomized 60 patients (61 hips) to receive either PE or XLPE cemented cups combined with a cemented stem. At 10 years postoperatively, 51 patients (52 hips) were evaluated for polyethylene wear and component migration estimation by radiostereometry, for radiolucent lines, bone densitometry, and Harris hip and pain scores. Revisions were recorded.


RESULTS
XLPE cups had a lower mean three-dimensional wear rate between 2 and 10 years compared to conventional PE hips: 0.005 mm/year versus 0.056 mm/year. We found no differences in cup migration, bone mineral density, radiolucencies, functional scores, and revision rate. There was a trend toward improved stem fixation in the XLPE group. The overall stem failure rate was comparably high, without influencing wear rate in XLPE hips.


CONCLUSIONS
XLPE displayed a low wear rate up to 10 years when used in cemented THA, but we found no clear benefits in any other parameters. Further research is needed to determine whether cemented THA designs with XLPE are less prone to stem loosening.


METHODS
Level I, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.
Department of Orthopaedics, Institution of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, 413 45 Gothenburg, Sweden. per-erik.johanson@vgregion.se
Per-Erik
PE
Johanson
Georgios
G
Digas
Peter
P
Herberts
Jonas
J
Thanner
Johan
J
Kärrholm
D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D001672:Biocompatible Materials; D001843:Bone Cements; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D011859:Radiography
D001672:Biocompatible Materials; D001843:Bone Cements; D020959:Polyethylene