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What is the natural history of asymptomatic pseudotumours in metal-on-metal hip resurfacing patients?

What is the natural history of asymptomatic pseudotumours in metal-on-metal hip resurfacing patients?

Hip Int 2016; 26(6): 522 - 530

Article Type: ORIGINAL RESEARCH ARTICLE

DOI:10.5301/hipint.5000387

Authors

Gulraj S. Matharu, Simon J. Ostlere, Hemant G. Pandit, David W. Murray

Abstract

Purpose

We assessed the natural history of asymptomatic pseudotumours associated with metal-on-metal hip resurfacings (MoMHRs), and factors associated with future revision.

Methods

In 2007-2008, we identified 25 MoMHRs (21 patients; mean age 59.9 years; 76% female) with asymptomatic pseudotumours. All patients underwent identical initial assessment (ultrasound, blood metal ions, radiographs, Oxford Hip Score [OHS]) and were considered asymptomatic because they denied experiencing hip symptoms, were satisfied with their MoMHR surgery, and had good or excellent OHSs (≥34). In 2012-2013, repeat assessments were performed in all non-revised patients.

Results

Revision for pseudotumour was performed/recommended in 15 MoMHRs (60%) at a mean 2.7 years (range 0.4-6.4 years) from initial assessment, with 14 developing symptoms before revision. Non-revised MoMHRs (n = 10) underwent repeat ultrasound at a mean 5.1 years (range 4.0-6.5 years) later, with no changes in pseudotumour volume (p = 0.956) or OHS (p = 0.065) between assessments. High blood cobalt (p = 0.0048) and chromium (p = 0.0162), large pseudotumours (p = 0.0458), low OHS (p = 0.0183), and bilateral MoMHRs (p = 0.049) predicted future revision. Patients with blood metal ions above established unilateral/bilateral thresholds and/or initial pseudotumours >30 cm3 had an 86.7% sensitivity, 70.0% specificity, 81.2% positive predictive value, and 77.8% negative predictive value for future revision.

Conclusions

MoMHR patients with initially asymptomatic pseudotumours often become symptomatic and require revision. Patients with high blood metal ions and/or pseudotumours >30 cm3 should remain under annual surveillance or be considered for revision (especially in patients also having lower initial OHSs, bilateral MoMHRs, and/or those becoming symptomatic). Less regular surveillance of patients outside these parameters appears acceptable.

Article History

Disclosures

Financial support: The Royal College of Surgeons of England and The Arthritis Research Trust provided GSM with funding in the form of a Surgical Research Fellowship.
Conflict of interest: GSM received salary funded by The Royal College of Surgeons of England and The Arthritis Research Trust. SO/HP/DM - none in relation to this particular study.

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Authors

Affiliations

  • Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Nuffield Orthopaedic Centre, Oxford - UK

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