The Failed TKA: What’s Causing the Problem’

    Although total knee arthroplasty (TKA) is generally a highly successful operation, there are many reasons it can fail – or appear to fail.

    According to Henry Clark, MD, from Mayo Clinic in Phoenix, Arizona, the first step in diagnosing and treating the failed TKA is to understand whether the symptoms are being caused by a problem with the knee itself (intrinsic factors) or another issue that is manifesting as pain and a problem with the implant (extrinsic factors).

    Is It Extrinsic or Intrinsic?

    Dr. Clarke outlined the extrinsic and intrinsic factors at the ICJR West meeting in Napa, California:

    Extrinsic Factors

    • Neurologic
    • Vascular claudication
    • Hip arthritis
    • Pes bursitis
    • Tendinitis (quadriceps, patellar)
    • Stress fracture

    Intrinsic Factors

    • Infection
    • Instability (extension, flexion)
    • Aseptic loosening
    • Mechanical failure
    • Polyethylene wear
    • Osteolysis
    • Component malpositioning (axial, rotational)
    • Arthrofibrosis
    • Soft tissue impingement (patellar clunk, overhanging components, popliteus impingement)
    • Patellar maltracking
    • Extensor mechanism rupture
    • Unresurfaced patella

    Patients affected by extrinsic factors unrelated to the implant will not benefit from knee revision because their knees have not failed. But they will need other treatment to resolve their issues, so it is important to quickly identify those patients and ensure they are managed appropriately.

    On the other hand, patients affected by intrinsic factors related to the implant may need a revision knee procedure. The list of intrinsic factors is lengthy, and as Dr. Clarke noted, a systematic workup will pare down the list to just a few possibilities.

    Indications for Revision

    Once the list has been narrowed down, a diagnosis can be made, generally on the basis of the history, physical exam, and x-rays. Dr. Clarke identified nine diagnoses for which a revision procedure is appropriate:

    • Instability
    • Soft tissue impingement
    • Extensor mechanism complications
    • Component failure
    • Periprosthetic fracture
    • Aseptic loosening
    • Infection
    • Particulate disease (synovitis, osteolysis)
    • Malpositioning (rotational/axial/sagital)

    It is important to note that the last three diagnoses require additional tests for confirmation.If the patient’s symptoms are not caused by one of these diagnoses, Dr. Clarke will treat the patient non-surgically.

    Surgical Pearl: Symptoms Are Not Diagnoses

    Dr. Clarke emphasized how crucial it is to know the diagnosis before taking the patient back to the operating room for a revision procedure. Non-specific symptoms such as pain, swelling, and stiffness are not valid diagnoses and cannot be the basis for the revision procedure. Performing a revision without identifying the reason for the patient’s symptoms has a low probability of success.

    Dr. Clarke’s presentation can be found here.