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Muscle atrophy and metal-on-metal hip implants

  • Reshid Berber
    ,
  • Michael Khoo
    ,
  • Erica Cook
    ,
  • Andrew Guppy
    ,
  • Jia Hua
    ,
  • Jonathan Miles
  • Royal National Orthopaedic Hospital NHS Trust
    ,
  • University of London
Research Output: Contribution to journal Article Peer-review

Open access

Abstract

Background and purpose — Muscle atrophy is seen in patients with metal-on-metal (MOM) hip implants, probably because of inflammatory destruction of the musculo-tendon junction. However, like pseudotumors, it is unclear when atrophy occurs and whether it progresses with time. Our objective was to determine whether muscle atrophy associated with MOM hip implants progresses with time. Patients and methods — We retrospectively reviewed 74 hips in 56 patients (32 of them women) using serial MRI. Median age was 59 (23–83) years. The median time post-implantation was 83 (35–142) months, and the median interval between scans was 11 months. Hip muscles were scored using the Pfirrmann system. The mean scores for muscle atrophy were compared between the first and second MRI scans. Blood cobalt and chromium concentrations were determined. Results — The median blood cobalt was 6.84 (0.24–90) ppb and median chromium level was 4.42 (0.20–45) ppb. The median Oxford hip score was 34 (5–48). The change in the gluteus minimus mean atrophy score between first and second MRI was 0.12 (p = 0.002). Mean change in the gluteus medius posterior portion (unaffected by surgical approach) was 0.08 (p = 0.01) and mean change in the inferior portion was 0.10 (p = 0.05). Mean pseudotumor grade increased by 0.18 (p = 0.02). Interpretation — Worsening muscle atrophy and worsening pseudotumor grade occur over a 1-year period in a substantial proportion of patients with MOM hip implants. Serial MRI helps to identify those patients who are at risk of developing worsening soft-tissue pathology. These patients should be considered for revision surgery before irreversible muscle destruction occurs.

Publication Information

Output type

Research Output: Contribution to journal Article Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 351

Journal (Volume, Issue Number)

Acta Orthopaedica (Volume 86, Issue 3)

Publication milestones

  • Published - 01/06/2015

Publication status

Published - 01/06/2015

ISSN

1745-3674

External Publication IDs

  • handle.net: 10547/558752
  • Scopus: 84929398606
  • ORCID: /0000-0003-4369-8202/work/32468977

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