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    What You Need to Know about Revising Metal-on-Metal Hips

    Wear and corrosion are common causes of failure in metal-on-metal (MoM) total hip arthroplasty (THA) and often lead to complicated revision procedures.

    At ICJR’s Winter Hip & Knee Course, Matthew S. Austin, MD, from The Rothman Institute in Philadelphia, Pennsylvania, offered his tips for revising a failed MoM THA.

    Dr. Austin noted that the revision causes and tips for managing these patients pertain not only to a failed MoM THA, but also to issues involving dual-modular components and trunnion corrosion.

    Here are Dr. Austin’s tips for managing these complicated cases:

    Tip #1: “When you hear hoof beats, think horses, not zebras,” he said. In other words, when a patient presents with a problematic THA, most of the time the issue will be infection or implant loosening. An adverse tissue reaction to metal should be on the list of potential causes, but it shouldn’t be the first thought.
     
    Tip #2: Preoperative planning is essential. “We are not nearly as good surgeons as we think we are,” Dr. Austin, advising attendees to carefully think through the surgical plan before going into the operating room. This includes:

    • Planning the surgery at least 1 to 2 weeks before the procedure to define the problem and develop multiple contingency plans
    • Knowing which components will be changed, which will be retained, and which are the safest options for the patient
    • Preparing to manage bone loss by ensuring that appropriate components and augments will be available at the time of surgery
    • Preparing to manage soft tissue loss by having options available to manage instability
    • Avoiding the use of intraoperative cell salvage, as this does not adequately remove cobalt and chromium ions

    Tip #3: Communicate with all staff members and keep them informed about the surgical plan and the type of equipment, implants, and grafts that will be needed.

    Tip #4: Simplify the equipment setup as much as possible. Dr. Austin recommends using a standardized set of instruments and removing all unnecessary tools, as this reduces setup time and the time it takes to find the right instrument during surgery.

    Tip #5: A quality exposure equals a quality outcome. Dr. Austin finds that a fully extensile approach is not necessary in all cases, but it is important to use an approach that can be extended should the need arise.

    Tip #6: Beware of “badness.” It is important to debride obviously necrotic soft tissue, but overly aggressive debridement can lead to dislocation and vascular and nerve injury. So be judicious in your debridement, Dr. Austin said.

    Tip #7: Let your patients know that “the jury is still out” on the results of revision THA. Not much data are available on the outcome of revision cases for MoM THA, MoM hip resurfacing, or taper corrosion [1]. In general, blood ion levels normalize in these cases, but complications and re-revision rates are high. Dr. Austin emphasized the importance of counseling patients about the potential for their surgery to be unsuccessful.

    Dr. Austin’s final advice: “Be careful, counsel your patients, and avoid disaster, because it is lurking around every corner with these metal-on-metal revisions.”

    Click the image above to watch Dr. Austin’s presentation.

    Reference

    1. Engh CA Jr, Ho H, Padgett DE. The surgical options and clinical evidence for treatment of wear or corrosion occurring with THA or TKA. Clin Orthop Relat Res. 2014 Dec;472(12):3674-86