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    A Revision THA Doesn’t Always Mean an Implant Has Failed

    Data from a joint registry can offer an early warning of an issue with a particular type of hip or knee implant.

    But do those data tell the whole story?

    The short answer is no, according to Thomas P. Schmalzried, MD, from the Joint Replacement Institute in Los Angeles, California.

    He expanded on that answer in his presentation on joint registries at the recent ICJR West meeting.

    Dr. Schmalzried noted that joint registries provide valuable data, but they have limitations: They typically report only the role of the implant in a revision procedure, failing to take into account the role of the patient, the role of the surgeon and the surgical procedure, and even the limitations of the device technology.

    He sees this focus on the device as a confluence of the technology age, the registry era, and the competitive and costly joint replacement market. But, he said, implants are more alike than they are different. The real variability comes from the patient and the surgeon/surgical procedure.

    Revision procedures, he said, should not be viewed as a failure of the device, but as a failure of the arthroplasty, factoring in the role of the patient, the surgeon, and the device.

    Registries, however, generally equate higher-than-expected revision rates with an underperforming implant. But other factors may be at play, such as patient comorbilities, the surgeon’s threshold for revision procedures, and limits of the technology that are not necessarily true device failures.

    Dr. Schmalzried examined data from 2 large databases – the Healthcare Cost and Utilization Project Nationwide Inpatient Sample [1] and the Australian Orthopaedic Association National Joint Replacement Registry [2] – and calculated that in 57% to 72% of revision total hip arthroplasty procedures for instability, loosening, infection, and periprosthetic fracture, the surgeon or the procedure may have played a role in the need for the revision.

    Conversely, he calculated that the implant had no role in 50% to 72% of the revisions.

    This suggests, Dr. Schmalzried said, the need to add what he calls “the surgeon effect” to registry data, which he explains in his presention.

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

    References

    1. Bozic KJ,Kurtz SM ,Lau E ,Ong K ,Vail TP , Berry DJ. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg Am 2009 Jan;91(1):128-33. doi: 10.2106/JBJS.H.00155.
    2. Australian Orthopaedic Association National Joint Replacement Registry. Annual Report. Adelaide:AOA; 2013. Accessed September 8, 2015.