More Evidence of Patient Benefits with Cross-Linked Polyethylene
In an OrthoBuzz post last year titled “Has Conventional Polyethylene Become Obsolete?,” we featured results from a small randomized trial that documented much-improved implant survival over 10 years with acetabular components made from cross-linked polyethylene (XLPE) compared with conventional polyethylene (CPE). In the August 1, 2018 issue of The Journal, we find further corroboration of the benefits realized by patients who receive XLPE acetabular components.
deSteiger et al. analyzed registry data involving more than 240,000 total hip arthroplasty (THA) patients and found markedly lower revision rates in those who received XPLE rather than CPE acetabular components. At a mean follow-up of 16 years, the cumulative percentage of revisions was 6.2% in the XPLE group versus 11.7% in the CPE group. Among patients <55 years of age at the time of THA, at 7 years there was a five-fold increase in revision rates for procedures done with CPE compared to those done with XLPE.
Because the authors observed that the between-group differences in revision rates became more pronounced over time, it is possible that this difference will continue to grow as more data is gathered. When we consider the vast number of THAs performed around the world each year, this XLPE-related decrease in revision rate could have a beneficial impact on millions of patients.
The documented success so far of XPLE is a clear case where understanding the nature of the original problem (polyethylene wear) and applying consistent and innovative research to find a solution have allowed patients worldwide to reap the benefits associated with THA, with some assurance that their hip replacement may, in fact, last for their rest of their life.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Has Conventional Polyethylene Become Obsolete in THA?
Highly cross-linked polyethylene (XLPE) has been in clinical use for nearly 15 years. In acetabular components for total hip arthroplasty (THA), XLPE’s superior wear characteristics and lower revision rates, relative to conventional polyethylene (PE), have been demonstrated in numerous studies. Here is one more: a 10-year Level I study in the October 18, 2017 issue of The Journal of Bone & Joint Surgery by Devane et al.
In this double-blinded, randomized trial, authors measured 2-D, 3-D, and volumetric wear (in mm or mm2), along with wear rates (mm/year), presence or absence of osteolysis, and revision rates in 91 patients at specified time intervals, up to a minimum of 10 years. The following results corroborate the general findings from most other studies on this topic:
- The mean 3-D wear rate among patients with the XLPE acetabular liner was 0.03 mm/yr, versus 0.27 mm/yr among patients with conventional PE.
- Eight percent of patients in the XLPE group showed radiographic evidence of osteolysis, versus 38% of patients in the PE group.
- Patients with the conventional PE liner had a significantly higher revision rate (14.6%) than those with the XLPE liner (1.9%).
There were no significant between-group differences in clinical outcome scores, including the Oxford Hip Score and SF-12 physical well-being score.
The authors note that “the longer-term implications of these findings are unclear,” but their calculations indicated that, through 20 years, none of the XLPE liners would wear through, but 6 of the conventional PE liners would require revision due to wear-through.
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