Abstract
Introduction
In Europe a femoral neck retaining stem (Metha, Aesculap Inc, Tuttlingen, Germany) has been reported with excellent midterm survivorship. We report on a US series and compare it to a review of reports in Europe over the past decade to determine if US experience matches that in Europe.
Methods
A review of published studies was performed on PubMed with search terms: Hip, replacement, arthroplasty, and Metha. We found four publications that met the criteria of reporting survivorship and reasons for revision surgery. The results from these four articles combined had 4179 THA with the Metha stem. After IRB approval three orthopaedic groups in the US were used to combine their experience over the last 11 years. These US sources had 824 surgeries performed between 2008–2019. We then reported on all revisions for comparison of survivorship.
Results
In the four publications [1–4] there was a reported 4.8% failure over 5–10 years for any reason. In the 824 US cases there were 3 periprosthetic infections, 4 periprosthetic fractures (all within 15 months) and 2 revisions for other reasons (thigh pain and leg length discrepancy). If stem revisions for any reason are taken into account the Kaplan-Meier Survivorship at 5 years is 94.0%, and if only aseptic loosening is considered then the survivorship is 99.1% at 5 years and 98.4% at 11 years.
Conclusion
Bone sparing implants for primary total hip replacement have seen the popularization of mid stems in the USA but a FNR stem has not seen significant popularity. This report from a three surgeon experience has excellent survivorship with two aseptic loosening cases both determined at time of periprosthetic fracture. Survivorship for this series at 11 years of 98.4% for aseptic loosening matches many reports of mid length or standard length primary total hip stems in national registry databases.
