10-year survival comparison of two cemented implants in primary total hip arthroplasty for osteoarthritis: a New Zealand regional study.

INTRODUCTION

Compare 10-year survival of the cemented highly crosslinked polyethylene Exeter® Rimfit™ (Rimfit) Cup and its predecessor, the ultra-high molecular weight polyethylene Exeter® Contemporary Flanged Cup™ (ECF), both with an Exeter® V40™ stem, in primary total hip arthroplasty (THA) for osteoarthritis in the Bay of Plenty region of NZ.

METHOD: We extracted national registry data for THA surgeries in the region between 1 January 2003 and 30 June 2023 and report the 10-year survival and reasons for revision of the two fully cemented implants (n = 495). We compared standard Kaplan-Meier estimates using the log-rank test. Cox proportional hazard models investigated the potential influence of six patient variables on the survival of each implant: sex, age, body mass index (BMI), ethnicity, American Society of Anesthesiologists (ASA) rating, and funding source (public/private).

RESULTS

No statistically significant difference in 10-year survival rate between the implants (p = 0.334) (ECF 95.6% [93.4, 97.9], Rimfit 97.0% [95.9, 98.2]) or statistically significant difference in revision reasons between the implants (p = 0.09) was noted. Cox regression revealed no statistically significant influence of any of the six patient variables on the 10-year survival of the ECF (p = 0.584) or Rimfit (p = 0.611).

CONCLUSION

Both implants exceeded 95% survival at 10-years, which is favourable compared to the corresponding 94.8% national survivorship of cemented implants in NZ. There is no statistically significant difference in the 10-year survival rate or reasons for revision of the two cemented implants compared in this region. The Rimfit appears a suitable alternative to the ECF, from a survival and revision perspective.