Continuous periprosthetic bone loss but preserved stability for a collum femoris-preserving stem: follow-up of a prospective cohort study of 21 patients with dualenergy X-ray absorptiometry and radiostereometric analysis with minimum 8 years of follow-up

Authors

  • Andreas Nyström Department of Surgical Sciences/Section of Orthopaedics, Uppsala University, Uppsala, Sweden
  • Demostenis Kiritopoulos Department of Surgical Sciences/Section of Orthopaedics, Uppsala University, Uppsala, Sweden
  • Hans Mallmin Department of Surgical Sciences/Section of Orthopaedics, Uppsala University, Uppsala, Sweden https://orcid.org/0000-0002-0074-7484
  • Stergios Lazarinis Department of Surgical Sciences/Section of Orthopaedics, Uppsala University, Uppsala, Sweden

DOI:

https://doi.org/10.2340/17453674.2021.1080

Keywords:

Arthroplasty, DEXA, Hip, Implants, RSA

Abstract

Background and purpose — We previously described a decrease in bone mineral density (BMD) in the calcar region 2 years after insertion of the collum femoris-preserving (CFP) stem, but the implants were stable. Now we have examined the long-term changes in periprosthetic BMD and stability of the CFP stem.

Patients and methods — We conducted a minimum 8-year follow-up of 21 patients from our original investigation. We examined periprosthetic BMD by dual-energy X-ray absorptiometry (DEXA) and implant stability by radiostereometric analysis (RSA).

Results — Between 2 and 8 years 1 stem was revised due to aseptic loosening. Between 2 and 8 years we found a 14% (95% confidence interval [CI] 9–19) reduction in BMD in Gruen zone 6 and 17% (CI 6–28) in Gruen zone 7. From baseline the reduction in BMD was 30% (CI 23–36) in Gruen zone 6, 39% (CI 31–47) in Gruen zone 7, and 19% (CI 14–23) in Gruen zone 2. Between 2 and 8 years, RSA (n = 17) showed a mean translation along the stem axis of 0.02mm (CI –0.02 to 0.06) and a mean rotation around the stem axis of 0.08° (CI –0.26 to 0.41). From baseline mean subsidence was 0.07 mm (CI –0.16 to 0.03) and mean rotation around the stem axis was 0.23° (CI –0.23 to 0.68) at 8 years.

Interpretation — There was continuous loss of proximomedial BMD at 8 years while the CFP stem remained stable. Proximal periprosthetic bone loss cannot be prevented by this stem.

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Published

2022-01-03

How to Cite

Nyström, A., Kiritopoulos, D., Mallmin, H., & Lazarinis, S. (2022). Continuous periprosthetic bone loss but preserved stability for a collum femoris-preserving stem: follow-up of a prospective cohort study of 21 patients with dualenergy X-ray absorptiometry and radiostereometric analysis with minimum 8 years of follow-up. Acta Orthopaedica, 93, 206–211. https://doi.org/10.2340/17453674.2021.1080

Issue

Section

Non-randomized clinical study