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    The Challenge of TKA in a Post-HTO Patient

    Dr. Samih Tarabichi reviews the technical aspects of revising a high tibial osteotomy to a total knee arthroplasty.

    The literature is not encouraging when it comes to high tibial osteotomy (HTO), said Samih Tarabichi, MD, as sooner or later many HTO patients will need to be revised to a total knee arthroplasty (TKA). In fact, revision rates for HTO are similar to those of unicondylar knee arthroplasty.

    Dr. Tarabichi, from Burjeel Hospital for Advanced Surgery in Dubai, United Arab Emirates, discussed the technical aspects of revising an HTO to a TKA at the recent ICJR Egypt meeting in Cairo.

    He said that TKA post-HTO is a more challenging procedure than a primary TKA, with:

    • Longer operative times
    • Difficulties with eversion of the patella
    • Increased number of lateral releases performed

    Functional outcomes 5 years after TKA in patients with a previous HTO tend to be inferior to those of primary TKA, Dr. Tarabichi said. Research has shown poor results in about 17% of cases, with a re-revision rate of 21% at less than 8 years of follow-up due to altered anatomy and significant balancing problems.

    He said, however, that current literature seems to be indicating that newer HTO techniques may improve outcomes in HTO patients who subsequently undergo TKA. For example, new open-wedge HTO techniques are more bone preserving than previous closed-wedge techniques. Patient-specific instruments are also showing promise, he said.

    In his presentation, Dr. Tarabichi reviewed the challenges involved surgeons need to be aware of when revising an HTO to a TKA:

    Soft Tissue Considerations

    • Determine whether the old incision can be used for the TKA or if the TKA incision should be far away from it. Ultimately, do minimal skin undermining.
    • Expect that patients will have stiffness and limited flexion that will need to be addressed. For example, Dr. Tarabichi said an anterior quadriceps release can improve range of motion and make the surgery easier.
    • Patients may also have patella Baja (which Dr. Tarabichi tends to ignore), contracted ligament, and instability. He recommends using a posterior stabilized implant rather than a cruciate retaining implant because of the ligament issues.

    Bony Challenges

    • The patient will typically have a deformed (shortened) metaphysis and possibly a deformed joint line. Dr. Tarabichi said he’s not as concerned about the restoring the joint line – he will balance the knee and make it stable and not worry about the joint line.
    • Non-union of the osteotomy is a possibility. In these cases, Dr. Tarabichi said he often does a simultaneous corrective osteotomy with a stemmed tibial implant.
    • Dr. Tarabichi urges surgeons to template the knee when converting an HTO to a TKA to avoid surprises with these bony issues intraoperatively.

    Hardware Removal

    • What to do with the HTO hardware is controversial. Some surgeons advocate removing it to reduce the risk of infection, and Dr. Tarabichi tends to agree with them.
    • However, if the hardware is not bothering the patient, would be difficult to remove, or does not affect the TKA, he would consider leaving it in place.
    • If he removes the hardware, he does it simultaneously with the TKA instead of a 2-stage procedure.

    Dr. Tarabichi concluded that when performing an HTO revision to a TKA:

    • Preoperative planning is important
    • Each case is different
    • Outcomes are improving
    • New HTO surgical techniques are improving results
    • CR implants do not work – use a PS or CCK implant
    • Remove hardware simultaneously with arthroplasty

    Click the image below to watch Dr. Tarabichi’s presentation.