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Revisions of Modular Metal-on-metal THA Have a High Risk of Early Complications

Jennings, Jason M., MD, DPT; White, Samuel, BS; Martin, J. Ryan, MD; Yang, Charlie C., MD; Miner, Todd M., MD; Dennis, Douglas A., MD

Clinical Orthopaedics and Related Research®: February 2019 - Volume 477 - Issue 2 - p 344–350
doi: 10.1097/CORR.0000000000000363

Background The risk of early complications is high after monoblock acetabular metal-on-metal (MoM) THA revisions. However, there is a paucity of evidence regarding clinical complications after isolated head-liner exchange of modular MoM THA.

Questions/purposes The purposes of this study were (1) to describe the frequency of early complications after an isolated head-liner exchange revision of modular MoM THA; and (2) to determine whether patients who experienced complications or dislocation after head-liner exchanges had higher serum chromium (Cr) or cobalt (Co) ion levels than those who did not.

Methods A review of our institution’s total joint registry retrospectively identified 53 patients who underwent 54 liner exchange revisions of a modular acetabular MoM THA. The study period was from April 2008 to April 2016 at a single tertiary care center. During this period, isolated head-liner exchanges (rather than more extensive revisions) were performed in patients if they did not have evidence of loosening of the acetabular or femoral components. Reasons for revision surgery included pain, mechanical symptoms, radiographic evidence of osteolysis, elevated serum metal ions, and MRI abnormalities with 40 of the 54 hips having pain or mechanical symptoms and 38 of 54 hips having multiple reasons for revision before surgery. Patients were excluded if they did not meet the minimum postrevision followup or had the modular liner exchange secondary to infection. All revisions were from a single manufacturer with one head-liner exchange of a MoM THA from another manufacturer excluded during the study period. The mean time from index MoM THA to modular exchange was 96 (SD ± 36) months. Because the focus of this study was early complications, we had a minimum 90-day followup duration for inclusion. Mean followup after revision was 15 months (SD ± 12); a total of 56% (30 of 54) had followup of at least 12 months’ duration. Complications (dislocation, infection) and reoperations were obtained by chart review performed by individuals other than the treating physician(s). Serum metal ion levels were obtained before head-liner exchange. The median serum Cr and Co levels were 6 µg/L (range, 0-76 µg/L) and 12 µg/L (range, 0-163 µg/L), respectively.

Results Of the 54 revision THAs, 15 (28%) developed complications. Nine (17%) occurred within 90 days of the revision surgery and 11 (20%) resulted in reoperation. The most common complication was dislocation (12 of 54 [22%]) with recurrent dislocation noted in eight of these 12 patients. All patients with recurrent dislocation continued to dislocate and underwent repeat revision. Patients with dislocation had higher median serum Cr and Co ion levels than those without dislocation (Cr: 24 [range, 11-76] versus 4 [range, 0-70], p = 0.001 [95% confidence interval {CI}, 10-57]; Co: 41 [range, 6-163] versus 8 [range, 0-133], p = 0.016 [95% CI, 6-141]). Three (6%) of the 54 patients underwent repeat surgery for deep space infection.

Conclusions Complications and reoperations are common after modular head-liner exchange in the setting of a failed MoM THA. Our study likely underestimates the frequency of complications and revisions because the followup period in this report was relatively short. Dislocation is the most common complication and elevated serum metal ion levels may be a predictor of dislocation. These findings are concerning and surgeons should be aware of the high complication risk associated with this procedure.

Level of Evidence Level IV, therapeutic study.

J. M. Jennings, C. C. Yang, T. M. Miner, D. A. Dennis, Colorado Joint Replacement, Denver, CO, USA

S. White, Icahn School of Medicine at Mount Sinai, New York, NY, USA

J. R. Martin, OrthoCarolina, Charlotte, NC, USA

J. M. Jennings, D. A. Dennis, Department of Mechanical and Materials Engineering, University of Denver, Denver, CO, USA

D. A. Dennis, Department of Orthopaedics, University of Colorado School of Medicine, Denver, CO, USA; and the Department of Biomedical Engineering, University of Tennessee, Knoxville, TN, USA

D. A. Dennis, Colorado Joint Replacement, 2535 S Downing Street, Suite 100, Denver, CO 80210, USA, email:

One of the authors (DAD) has or may receive payments or benefits from DePuy (Warsaw, IN, USA), Innomed (Savannah, GA, USA), Joint Vue (Columbus, OH, USA), and Wolters Kluwer Health (Philadelphia, PA, USA) not related to this work. One of the authors (JMJ) has or may receive payments or benefits from DePuy, Total Joint Orthopedics (Salt Lake City, UT, USA), and Xenex (San Antonio, TX, USA) not related to this work. One of the authors (CCY) has or may receive payments or benefits from DePuy, Medtronic (Minneapolis, MN, USA), and Zimmer (Warsaw, IN, USA) not related to this work. One of the authors (TMM) has or may receive payments or benefits from DePuy and Zimmer not related to this work.

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 prior to clinical use.

Each author certifies that his institution approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.

This work was performed at Colorado Joint Replacement, Denver, CO, USA.

Received January 30, 2018

Received in revised form April 25, 2018

Accepted May 07, 2018

© 2019 Lippincott Williams & Wilkins LWW
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