Comparison of extracapsular pseudotumors seen in magnetic resonance imaging and in revision surgery of 167 failed metal-on-metal hip replacements
DOI:
https://doi.org/10.3109/17453674.2014.934189Abstract
Background and purpose — Magnetic resonance imaging (MRI) is important for detecting extracapsular pseudotumors, but there is little information on the accuracy of MRI and appropriate intervals for repeated imaging. We evaluated the sensitivity and specificity of MRI for detecting pseudotumors in 155 patients (167 hips) with metal-on-metal (MoM) hip arthroplasties that failed due to adverse reactions to metal debris (ARMD).Methods — Preoperative MRIs were performed with two 1.5 T MRI scanners and graded by a senior musculoskeletal radiologist using a previously described MRI pseudotumor grading system. Revision findings were retrieved from surgical notes, and pseudotumors were retrospectively graded as fluid-filled, mixed-type, or solid.Results — The sensitivity of MRI was 71% and the specificity was 87% for detecting extracapsular pseudotumors. The sensitivity was 88% (95% CI: 70–96) when MRI was performed less than 3 months before the revision surgery. Interestingly, when the time that elapsed between MRI and revision was more than 1 year, the sensitivity calculated was only 29% (95% CI: 14–56). Comparison between MRI and revision classifications gave moderate agreement (Cohen’s kappa = 0.4).Interpretation — A recent MRI predicts the presence of a pseudotumor well, but there is more discrepancy when the MRI examination is over a year old, most likely due to the formation of new pseudotumors. 1 year could be a justifiable limit for considering a new MRI if development of ARMD is suspected. MRI images over a year old should not be used in decision making or in planning of revision surgery for MoM hips.Downloads
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Published
2014-09-01
How to Cite
Lainiala, O., Elo, P., Reito, A., Pajamäki, J., Puolakka, T., & Eskelinen, A. (2014). Comparison of extracapsular pseudotumors seen in magnetic resonance imaging and in revision surgery of 167 failed metal-on-metal hip replacements. Acta Orthopaedica, 85(5), 474–479. https://doi.org/10.3109/17453674.2014.934189
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Acta Orthopaedica (Scandinavica) content is available freely online as from volume 1, 1930. The journal owner owns the copyright for all material published until volume 80, 2009. As of June 2009, the journal has however been published fully Open Access, meaning the authors retain copyright to their work. As of June 2009, articles have been published under CC-BY-NC or CC-BY licenses, unless otherwise specified.