Survivorship of Highly Cross-Linked Polyethylene in Total Hip Arthroplasty: 20-Year Follow-Up.

BACKGROUND

In this study, we investigated the 20-year wear properties and survivorship of a highly cross-linked polyethylene liner (PE) used in total hip arthroplasty. We expected wear properties of less than one mm/year and improved survivorship when compared to the current literature after 20 years of follow-up.

METHODS

A retrospective review of our institution's electronic medical record was conducted from 1999 to 2003. Patients who underwent total hip arthroplasty by a single fellowship-trained orthopedic surgeon with placement of a highly cross-linked polyethylene with 20-year follow-up were included. Patients who lacked appropriate follow-up or adequate electronic medical record data, or who were unreachable via telephone were excluded. In total, 89 patients were reviewed to determine revision rates. In addition, the earliest hip radiographs were compared to recent follow-up images via an independent reviewer utilizing computer software to quantify wear.

RESULTS

The majority of patients underwent surgery secondary to end-stage primary osteoarthritis (70.8%). Out of 89 patients, there were seven revisions (7.9%). Of those revisions, one was secondary to osteolysis (14.3%), two were due to infection (28.6%), and four were due to dislocation (57.1%). There were 66 patients who underwent wear rate analysis, showing a mean linear wear rate of 0.06 ± 0.07 (mm/year). The mean volumetric wear rate was 11.8 ± 13.2 (mm3/year). At 20 years, the survival probability of this PE for all-cause revision was 93.5% (95% confidence interval: 88.2 to 99.2), while the survival probability for revision due to osteolysis was 98.6% (95% confidence interval: 95.9 to 99.9).

CONCLUSIONS

When utilizing a highly cross-linked, electron beam-radiated, and melt-annealed PE, only one patient underwent revision for osteolysis. Implementation of these liners demonstrates minimal volumetric and linear wear rates and shows excellent long-term survivability after 20 years follow-up.