Abstract
Purpose
Cross-linking of polyethylene greatly reduces its wear rate in hip simulator studies. We conducted a systematic review and meta-analysis of randomized controlled trials comparing cross-linked to conventional polyethylene liners for total hip arthroplasty to determine if there is a clinical reduction of: 1) wear rates, 2) radiographic osteolysis, and 3) need for total hip revision.
Method
A systematic search of MEDLINE, EMBASE, and COCHRANE databases was conducted from inception to May 2010 for all trials involving the use of cross-linked polyethylene for total hip arthroplasty. Eligibility for inclusion in the review was: use of a random allocation of treatments; a treatment arm receiving cross-linked polyethylene and a treatment arm receiving conventional polyethylene for total hip arthroplasty; and use of radiographic wear as an outcome measure. Eligible studies were obtained and read in full by two co-authors who then independently applied the Checklist to Evaluate a Report of a Nonpharmacological Trial to each study. Pooled mean differences were calculated for the following continuous outcomes: bedding-in, linear wear rate, three dimensional linear wear rate, volumetric wear rate, and total linear wear. Pooled risk ratios were calculated for radiographic osteolysis and revision hip arthroplasty.
Results
The literature search strategy identified 194 potential studies of which 12 met inclusion criteria. All studies reported a significant reduction in radiographic wear with cross-linked polyethylene. Pooled mean differences for linear wear rate, three dimensional linear wear rate, volumetric wear rate, and total linear wear were all significantly reduced for cross-linked polyethylene. The risk ratio for radiographic osteolysis was 0.40 (95% C.I. of 0.27 to 0.58; p<0.01; I2=0%), favoring cross-linked polyethylene. There were no significant differences in need for revision total hip arthroplasty or amount of bedding-in.
Conclusion
Cross-linked polyethylene liners demonstrate reduced radiographic wear and osteolysis up to 8 years after implantation. Follow up is not long enough to show a difference in need for revision total hip arthroplasty. Cross-linked polyethylene should be considered for young patients undergoing total hip arthroplasty.
