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    Evaluating Acetabular Bone Loss in Revision THA

    Reconstructing the acetabulum in revision total hip arthroplasty requires a systematic approach that starts with 4 key questions:

    • Where is the bone loss?
    • How bad is the bone loss?
    • What is the quality and location of the remaining bone?
    • Is there discontinuity?

    James A. Browne, MD, told attendees at ICJR’s 7th Annual Revision Hip & Knee Course that following Paprosky’s classification system for acetabular bone loss not only provides answers to these questions, but also offers a framework for the reconstruction strategy.

    RELATED: Register for ICJR’s 8th Annual Revision Hip & Knee Course, June 17-19

    To determine where the bone loss has occurred and how bad it is, the surgeon should evaluate:

    • Superior migration of the hip center, which gives a window into superior acetabular dome loss
    • Osteolysis of the tear drop, which provides valuable information about inferomedial and medial wall bone loss
    • Ischial osteolysis, which describes the degree of posterior column bone loss
    • Kohler’s line (ilioischial line), which offers insight into anterosuperior column and medial wall bone loss

    The goal is to determine whether the columns are supportive, which is critical to the stability and fixation of a hemispherical shell in the revision procedure. Good contact must be achieved between the anterosuperior and posteroinferior bone. If cup migration exceeds the diameter of the acetabulum, it is likely that at least one of the columns is no longer supportive, Dr. Browne said.

    Anteroposterior (AP) pelvis, true lateral, and Judet view radiographs will show whether pelvic discontinuity is present. Research from Mayo Clinic shows that 3 radiographic features on the AP pelvis radiograph are reliable indicators of discontinuity: [1]

    • Visible fracture line
    • Medial migration of the inferior pelvis
    • Asymmetry of the obturator foramen

    The general principles for reconstruction, Dr. Brown said, include:

    • Achieve rigid fixation and mechanical stability on the host bone
    • Maximize the porous surface area of the cup against viable host bone for good bone ingrowth
    • Restore biomechanics, with the goal of getting the hip center within 1 cm of the patient’s normal anatomy
    • Retore bone stock whenever possible, using particulate bone grafting of cavitary defects
    • Remember that cups don’t fail from excessive support or fixation; add augments or a cup cage if there is a concern about fixation
    • Ensure adequate fixation of the inferior hemisphere by using additional screws whenever possible

    Click the image above to watch the presentation and learn more from Dr. Browne about treatment options for the various classifications of bone loss.

    Faculty Bio

    James A. Browne, MD, is the Alfred R. Shands Associate Professor in the Adult Reconstruction Division of Orthopaedic Surgery at the University of Virginia in Charlottesville. He serves as the Vice Chair of Clinical Operations and Division Head of Adult Reconstruction. Dr. Browne is also the physician co-lead of the Musculoskeletal Service Line.

    Disclosures: Dr. Browne has disclosed that he receives royalties from and is a paid consultant for DJO, that he is a paid consultant for OsteoRemedies, and that he has stock or stock options in Radlink.

    Reference

    1. Martin JR, Barrett IJ, Sierra RJ, Lewallen DG, Berry DJ. Preoperative radiographic evaluation of patients with pelvic discontinuity. J Arthroplasty. 2016 May;31(5):1053-6. doi: 10.1016/j.arth.2015.11.024. Epub 2015 Nov 26.