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    CHALLENGING CASES: Managing Bone Loss in Revision TKA

    Revision rates for total knee arthroplasty (TKA) range from 8% to 10%, with multiple etiologies identified for these failures.

    One etiology is implant loosening with osteolysis and bone loss, and at the ICJR South/RLO Course, Giles R. Scuderi, MD, from Lenox Hill Hospital in New York, reviewed the treatment options for bone loss in revision TKA. He also discussed his preferred techniques for different types of bone defects.

    When assessing the amount of bone loss, the surgeon should determine the size, location, geometry, and shape of the lesions; these factors will influence how a defect is managed during revision surgery. Dr. Scuderi said that only about 17% of lesions show up on regular radiographs. [1] CT scans better reveal the extent of these lesions, which helps with preoperative planning.

    Dr. Scuderi uses the AORI (Anderson) Classification to determine the type of bone defect and the appropriate treatment.

    AORI Type 1

    Dr. Scuderi manages these smaller (< 5 mm), contained defects using bone cement or impaction bone grafts.

    AORI Type 2

    Type 2 defects, which are very common, have damage to the metaphyseal bone causing component subsidence; they may also have significant osteolysis. Most modern component systems have modular augmentation that allows intraoperative customization to manage these defects. For contained metaphyseal Type 2 defects, metaphyseal sleeves can be used.

    AORI Type 3

    These defects have massive osteolysis with deficient metaphyseal segments at or above the femoral condyles, or at or below the tibial tubercle. If these defects are unicondylar, modular metal augments may be used. For bicondylar defects, management options depend on the extent of the defect and the age of the patient:

    • Modular augments including trabecular metal (TM) cones
    • Structural bone grafts and stems (younger patients)
    • Hinge or tumor prostheses (older patients)

    When applicable, Dr. Scuderi uses TM cones, as these can be used with any revision system, come in multiple sizes and dimensions, and eliminate the concerns traditionally associated with bone grafts.

    • On the tibial side, TM cones help restore the cortical rim, creating a stable base for the implant. TM allows for osseous integration of the metaphyseal cone, and the tibial implant is cemented to the cone. When using TM cones, a cemented or press-fit stem is used.
    • On the femoral side, TM cones help reestablish metaphyseal bone. Additional augments can help restore the distal joint line and posterior condyles.

    Dr. Scuderi reviewed the treatment algorithm he uses based on the type of bone defect, and noted that a combination of techniques is often needed to address the various types of defects present in a single revision TKA.

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

    Disclosures

    Dr. Scuderi has disclosed that he is a a consultant and receives royalties from Zimmer Biomet; that he is a consultant for Medtronic, ConvaTec, Pacira Pharmaceuticals, and Merz Pharmaceuticals; that he receives research support from Pacira Pharmaceuticals; and that he receives book royalties from Springer, Elsevier, Theime, and World Scientific.

    Reference

    1. Reish TG, Clarke HD, Scuderi GR, Math KR, Scott WN. Use of multi-detector computed tomography for the detection of periprosthetic osteolysis in total knee arthroplasty. J Knee Surg 2006;19:259–264