Migration of the uncemented Echo Bi-Metric and Bi-Metric THA stems: a randomized controlled RSA study involving 62 patients with 24-month follow-up

Authors

  • Karen Dyreborg Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, Denmark; Department of Hip and Knee Surgery, Herlev-Gentofte University Hospital, Hellerup, Denmark
  • Mikkel R Andersen Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, Denmark
  • Nikolaj Winther Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, Denmark
  • Søren Solgaard Department of Hip and Knee Surgery, Herlev-Gentofte University Hospital, Hellerup, Denmark
  • Gunnar Flivik Department of Orthopedics, Lund University and Skåne University Hospital, Lund, Sweden
  • Michael M Petersen Department of Orthopaedic Surgery, Rigshospitalet, University of Copenhagen, Denmark

DOI:

https://doi.org/10.1080/17453674.2020.1802682

Abstract

Background and purpose — Despite the good results after total hip arthroplasty (THA), new implants are continu- ously being developed to improve durability. The Echo Bi- Metric (EBM) THA stem is the successor to the Bi-Metric (BM) THA stem. The EBM stem includes many of the fea- tures of the BM stem, but minor changes in the design might improve the clinical performance. We compared the migra- tion behavior with radiostereometric analysis (RSA) of the EBM stem and the BM stem at 24 months and evaluated the clinical outcome.

Patients and methods — We randomized 62 patients with osteoarthritis (mean age 64 years, female/male 28/34) scheduled for an uncemented THA to receive either an EBM or a BM THA stem. We performed RSA within 1 week after surgery and at 3, 6, 12, and 24 months. The clinical outcome was evaluated using Harris Hip Score (HHS) and Oxford Hip Score (OHS).

Results — At 24 months, we found no statistically sig- nificant differences in migration between the two implants. During the first 3 months both the EBM and the BM stems showed visible subsidence (2.5 mm and 2.2 mm respec- tively), and retroversion (2.5° and 2.2° respectively), but after 3 months this stabilized. The expected increase in HHS and OHS was similar between the groups.

Interpretation — The EBM stem showed a migration at 24 months not different from the BM stem, and both stems display satisfying clinical results.

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Published

2020-08-06

How to Cite

Dyreborg, K. ., Andersen , M. R. ., Winther, N. ., Solgaard, S. ., Flivik, G. ., & Petersen , M. M. . (2020). Migration of the uncemented Echo Bi-Metric and Bi-Metric THA stems: a randomized controlled RSA study involving 62 patients with 24-month follow-up. Acta Orthopaedica, 91(6), 693–698 . https://doi.org/10.1080/17453674.2020.1802682