Why THAs Fail, and How Technology Can Help

    Total hip arthroplasty (THA) was a game-changing operation when it was introduced by Sir John Charnley in the 1960s.

    Since then, Gregory G. Polkowski II, MD, MS, told attendees as ICJR’s inaugural Emerging Technologies in Joint Replacement course, refinements to the techniques and technologies used in THA have helped to drive the success of the procedure.

    But the THAs of the past were not without issues, he said, including:

    • Fixation problems related to poor cement technique
    • Dislocation related to the necessity of using small head sizes
    • Osteolysis related to the use of conventional polyethylene in bearing surfaces

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    Advances in THA have changed the way surgeons look at today’s failure modes.

    With the move to cementless fixation, implant loosening from poor cement technique is not the problem it used to be. Dr. Polkowski, from Vanderbilt Orthopaedic Institute in Nashville, Tennessee, says aseptic loosening today is the result of failed ingrowth related to technical issues such as a stem/femoral geometric mismatch.

    Cementless fixation has brought about another problem: periprosthetic fractures. These can occur during or after surgery, before ingrowth occurs.

    Dislocation is still an issue, occurring in 0.1% to 2% of THAs, depending on the study. The use of larger femoral heads, made possible by highly cross-linked polyethylene bearings, has reduced the incidence of dislocations. Issues with femoral anteversion and spinal pathology are the culprits for dislocation today, Dr. Polkowski said.

    The use of metal-on-metal bearings is a relatively unique mode of failure in modern THAs, Dr. Polkowski said, that has resulted in the recall of metal-on-metal bearings. Surgeons have also had to deal with complications from modular junctions and taper corrosion from the use of dissimilar metals.

    Time will tell, Dr. Polkowski said, whether dual-mobility implants that use a cobalt chromium liner and large titanium socket will cause the same issues as metal-on-metal implants.

    The orthopaedic profession is at a crossroads, Dr. Polkowski said: The technology of the future will have to be leveraged against patient outcomes. Industry, and surgeons, will have a difficult time “selling” new technology if it cannot be proven to result in better outcomes.

    Click on the image above to watch Dr. Polkowski’s presentation from Emerging Technologies in Joint Replacement.

    After Dr. Polkowski’s presentation, faculty members addressed possible solutions to the issues he outlined. Click on the images below to watch their presentations.

    Fluoroscopy Distortion Correction Using Fluoroscopic Grid Technology in THA
    Jeffrey T.
    Hodrick MD

    Digital Guidance Technology in THA
    Preetesh D. Patel MD

    Active Robotics in THA
    Cory L.
    Calendine MD

    Custom Triflange Cup in THA: Results and Lessons Learned at 20 Years
    Michael J. Christie MD

    Technologic Advances in Revision Total Hip Arthroplasty
    D. Patel MD