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Analysis

Follow-up for patients with metal-on-metal hip replacements: are the new MHRA recommendations justified?

BMJ 2018; 360 doi: https://doi.org/10.1136/bmj.k566 (Published 13 February 2018) Cite this as: BMJ 2018;360:k566
  1. Gulraj S Matharu, orthopaedic registrar1 2,
  2. Andrew Judge, professor of translational statistics1 2 3,
  3. Hemant G Pandit, professor of orthopaedic surgery1 4,
  4. David W Murray, professor of orthopaedic surgery1
  1. 1Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
  2. 2Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
  3. 3MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton, UK
  4. 4Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, UK
  1. Correspondence to: G S Matharu gsm{at}doctors.org.uk

Recent MHRA guidance for the surveillance of people with metal-on-metal hip replacements are onerous, costly, and insufficiently evidence based, argue Gulraj Matharu and colleagues

Metal-on-metal hips were commonly used in young active patients with arthritis, with about 1.5 million implanted worldwide.123 However, the devices experienced high short term failure rates,45 and many patients have had to have revision surgery because of abnormal reactions to materials generated by the implants (collectively termed adverse reactions to metal debris).126 Metal-on-metal hip implants are now rarely used.12

Failure of conventional hip implants is associated with symptomatic bone damage and requires revision with a larger implant. However, adverse reactions to metal debris from metal-on-metal implants are associated with destruction of soft tissue (muscles, tendons, neurovasculature) as well as bone. The soft tissue destruction is often irreparable,78 resulting in many patients doing poorly after revision procedures.8 Furthermore, irreversible bone and soft tissue damage can occur without noticeable symptoms.9 A few patients also develop systemic symptoms from exposure to high levels of metal ions, though these usually resolve after revision surgery (box 1). Reassuringly, large cohort studies have reported that patients with metal-on-metal hips are not at increased risk of cancer, heart failure, or death compared with patients with conventional hip replacements.1314151617

Box 1

Systemic effects of high metal ion exposure101112

Neurological

  • Hearing impairment or loss

  • Visual impairment or loss

  • Peripheral neuropathy

  • Cognitive impairment

Cardiovascular

  • Cardiomyopathy/heart failure

  • Breathlessness

Endocrine

  • Hypothyroidism

  • Malaise

  • Depression

RETURN TO TEXT

Regulatory authorities worldwide therefore recommend regular follow-up of patients with metal-on-metal implants in order to identify and treat adverse reactions early, and hopefully improve outcomes.1819202122 Surveillance can include clinical review, measurement of blood metal ion levels (surrogate marker of implant wear), hip radiography, and cross sectional imaging (ultrasonography or magnetic resonance imaging (MRI)). …

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