Highly Crosslinked Polyethylene Does Not Reduce Aseptic Loosening in Cemented THA 10-year Findings of a Randomized Study

Abstract

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 longterm wear characteristics are unknown and it is unclear whether reduced wear particle burden improves function and survival of cemented hip arthroplasty. Questions/purposes 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.

Low Wear Rates Seen in THAs With Highly Crosslinked Polyethylene at 9 to 14 Years in Patients Younger Than Age 50 Years

“…Previous reports on this population with conventional polyethylene have been associated with unacceptably high component loosening and osteolysis [3,7,9,23,29,32,34,35]. Highly crosslinked polyethylene has had much less wear and osteolysis, even in the younger population [1,21,22,24,25]. Use of a counterface material such as ceramic or Oxinium to further decrease wear is also appealing.…”

“…The low rate of HXLPE wear in our study is below the assumed wear threshold to produce particulate debris that is sufficient to cause osteolysis, assuming the particles are of comparable biologic activity and because of this, the survival should be equal to or improved when compared with conventional polyethylene. Two prospective randomized studies have demonstrated less wear but have not shown a reduction in aseptic loosening [17,21]. The studies include a relatively small number of patients (60, 54) randomized with one study reporting one failure of a cemented femur in the standard polyethylene group and two failures in the HXLPE group (p = 1.0) [21].…”

“…Two prospective randomized studies have demonstrated less wear but have not shown a reduction in aseptic loosening [17,21]. The studies include a relatively small number of patients (60, 54) randomized with one study reporting one failure of a cemented femur in the standard polyethylene group and two failures in the HXLPE group (p = 1.0) [21]. The other study identified no failures in either group [17].…”

“…None of the patients required revision surgery or had evidence of osteolysis or loosening. The remaining 10-year followup studies include patients with a mean age greater than 50 [2,4,12,14,17,21,37].…”

Do Alumina Matrix Composite Bearings Decrease Hip Noises and Bearing Fractures at a Minimum of 5 Years After THA?

“…Although contemporary THAs with highly crosslinked polyethylene (HXLPE) or hard-on-hard bearings offer great hope for reducing wear, the reduction in wear observed in THAs with HXLPE appears to be not quite as dramatic as seen in those with hard-on-hard bearings [19,32], and those with metal-on-metal bearings have problematic issues such as hypersensitivity and pseudotumors [34].…”