The John Charnley Award: Diagnostic Accuracy of MRI Versus Ultrasound for Detecting Pseudotumors in Asymptomatic Metal-on-Metal THA

Abstract

Background The prevalence of pseudotumors in patients with large-head metal-on-metal (MOM) THA has been the subject of implant recalls and warnings from various regulatory agencies. To date, there is no consensus on whether ultrasound or MRI is superior for the detection of pseudotumors. Questions/purposes We prospectively compared ultrasound to MRI for pseudotumor detection in an asymptomatic cohort of patients with MOM THAs. We also compared ultrasound to MRI for assessment of pseudotumor growth and progressive soft tissue involvement at a 6-month interval. Methods We enrolled 40 patients with large-head MOM THAs in the study. The mean age was 54 years (range, 34-76 years). The mean time from surgery was 54 months (range, 40-81 months). There were 28 men and 12 women. All patients underwent ultrasound and MRI using slice encoding for metal artifact correction. The gold standard was defined as follows: if both ultrasound and MRI agreed, this was interpreted as concordant and the result was considered accurate. (Toronto, Ontario, Canada). The institution of one or more of the authors (BAH) has received, during the study period, funding from GE Healthcare (Waukesha, WI, USA) and the NIH (Bethesda, MD, USA). One of the authors (DSG) certifies that he or she has received or may receive payments or benefits, during the study period, an amount of USD 10,000 to USD 100,000 from Zimmer, Inc. One of the authors (CPD) certifies that he or she has received or may receive payments or benefits, during the study period, an amount of USD 10,000 to USD 100,000 from Zimmer, Inc, and an amount of USD 10,000 to USD 100,000 from DePuy Synthes Canada Ltd. One of the authors (BAM) certifies that he or she has received or may receive payments or benefits, during the study period, an amount of USD 10,000 to USD 100,000 from Zimmer, Inc. The remaining authors (BAH, DFW, BBF) certify that they have no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use. Each author certifies that the human protocol for this investigation was approved by the appropriate ethics committee at his or her institution, that all investigations were conducted in conformity with the ethical principles of research, and that informed consent for participation in the study was obtained. This work was performed at the Departments of Orthopaedics and Radiology, University of British Columbia (Vancouver, British Columbia, Canada) and at Vancouver General Hospital (Vancouver, British Columbia...

Do Patients With a Failed Metal-on-metal Hip Implant With a Pseudotumor Present Differences in Their Peripheral Blood Lymphocyte Subpopulations?

“…Patients with a well-functioning MoM hip implant (nine resurfacings and three THAs) at 5 or more years postimplantation who did not have a pseudotumor, as demonstrated sonographically [8], served as the control group. All ultrasounds were performed by a fellowshiptrained musculoskeletal radiologist (RF).…”

“…Patients with a well-functioning implant were assessed at the latest postoperative clinical followup (6 ± 1 years [mean ± SD]; range, 5-8 years) with the WOMAC and the UCLA activity scores. WOMAC scores were 100 (94-100) (median with interquartile range), 88 (75-88), 98 (95-100), and 94 (92-97) for pain, stiffness, function, and total score, respectively, and the UCLA score was 8 (6)(7)(8). Patients with a WOMAC score lower than 75 for stiffness and lower than 80 for pain, function, and total score, and/or a UCLA score lower than 6 (with 10 being the best score) were excluded from the study.…”

“…In addition, not all patients with high metal ion levels and high wear develop an adverse tissue reaction [4,6,10]. Radiological investigation using sonography is currently recommended to confirm a pseudotumor diagnosis [8]. Unfortunately, imaging does not allow the differentiation between aggressive and benign lesions, and how to assess the severity and the progression of these lesions remains elusive.…”

The Surgical Options and Clinical Evidence for Treatment of Wear or Corrosion Occurring With THA or TKA

“…This observation implies that earlier recognition of the clinical entity and diagnosis prompting earlier intervention may play a role in reducing the complications associated with wear and corrosion. Current research is focusing on routine use of three-dimensional imaging to diagnose corrosion and MoM wear problems before there is extensive soft tissue damage [16,35]. Many of the studies we identified also mentioned the use of metal level testing.…”

What Are the Advantages and Disadvantages of Imaging Modalities to Diagnose Wear-related Corrosion Problems?

“…Proposed advantages of MoM bearings in THA include decreased wear, lower frequencies of dislocation, greater ROM, and an improved ability to withstand high-impact activities [14]. However, concerns have arisen with the use of large MoM bearings as a result of reports of catastrophic aseptic reactions resulting in soft tissue destruction, periprosthetic osteolysis, and associated complications [2,13,15,21,22].…”