Curb Your Enthusiasm about Stem Cells for Knee OA

Mark Miller, MD is a professor of orthopaedic surgery at the University of Virginia, founder and co-director of the Miller Review Courses, and former deputy editor for sports medicine at JBJS. In a piece he authored recently for The Conversation, Dr. Miller labeled stem-cell treatments for knee osteoarthritis (OA) “unproven, expensive, and potentially dangerous.”

About 2 years ago, Dr. Miller himself underwent bilateral knee replacements for severe knee arthritis. He understands why patients may fall prey to misleading marketing hype that claims stem cell treatments can help people postpone or entirely avoid knee replacement. (See related OrthoBuzz post.) “My mission,” he writes, is to “try to keep the enthusiasm regarding new cutting-edge options in check,” adding that “the excitement about stem cells has outpaced the science,” especially when it comes to knee OA.

Although stem cell injections have been promoted as a way to regenerate cartilage in arthritic joints, Dr. Miller echoes the American Association of Hip and Knee Surgeons when he says that “there are no proven…therapies that can delay or reverse the progressive joint destruction that occurs with osteoarthritis.” Moreover, the do-no-harm part of the Hippocratic oath requires doctors to give their patients “a clear picture of the potential benefits and side effects of their treatment options,” writes Dr. Miller, who cited a December 20, 2018 New York Times article describing 12 patients who were hospitalized for serious infections after receiving stem cell injections into their knees, shoulders, or spines.

For their part, Dr. Miller says patients should employ the “buyer beware” concept because stem cell therapy for osteoarthritis is not only unproven but also expensive—and usually not covered by medical insurance. The best approach to knee OA, says Dr. Miller, is what is nowadays called shared decision making: “Physicians need to work closely with patients to help them understand their options and which choice may be best for them.”

6 thoughts on “Curb Your Enthusiasm about Stem Cells for Knee OA

  1. Thank you Dr Miller for providing a clear understanding of the role that stem cell technology still considered an investigational role and not a main therapeutic choice at present for OA of the joints.
    Dr David Brown, Rheumatologist,Pasadena,CA

  2. Local stem cell hawks cite a study from Europe showing a 7-year bell-shaped improvement in cartilage depth before regression to baseline after stem cell treatment. They intimated that politics (orthopedics surgeons do not want to give up the gravy train of knee replacements) lie behind our government not allowing harvest of stem cells from discarded placental tissue. Of course they did not share the concentration of stem cells in the European injectate, nor the concentration of “stem cellls” in their adipose tissue derived injectate. Thanks to Dr Miller for this enlightening diagram. I feel there is often a fine line between trying to help with what you have and greed.

  3. For the last 3 to 4 years, I have been telling my patients exactly the same thing. “If you want to try, it’s a gamble, not a scientifically proven procedure.”

  4. While PRP, stem cells, and exosomes are indeed still considered investigational, your bias is quite evident.

    This study ( cites about 700,000 total knees performed in a year, with an incidence of infection of around 2% (14,000 infections) after joint surgery vs 12 for stem cells.

    To get a better handle on the stem cell number, we need an idea of the number of persons who received injections; 1000 injections with 14 infections would still be 1.4% infection rate. The truth is we don’t know.

    Here is the article I am guessing is quoted ( It had nothing to do with the physician; the infections came from the supplier. Amniotic fluid and cord blood do not contain live stem cells. If they were live, then we would have an allograft product, which is not allowed under the FDA rules published in November of 2018. If they contained “live” cells, they would be considered a 361 product and need to go through the the drug trial leg for approval. Mesenchymal stem cells (MSCs) derived from the patient’s own bone marrow fall under the 351 leg, which is allowed by the FDA.

    Cord blood and amniotic fluid do contain multiple cytokines, growth factors, and chemokines that can impact the inflamatory micro-environment of an arthritic knee. When harvesting MSC’s from a patient’s hip crest and all through the concentration process, strict sterile technique must be observed to minimize the risk of infection. But look at the number of knee infections in spite of dramatic measures taken now.

  5. I agree with the statement from Scott Jahnke. I received MSC’s from a physician using the Regenexx method. I was able to go back to Snowboarding and wake boarding, which I had quit for 6 years prior. The treatment was not an unlimited success, but I look at it as a management plan to keep the eventual TKR later in my life.
    There are no panacea treatments, when it comes to knee arthritis. All treatments have risks. I do encourage my patients who are interested in PRP and “Stem Cell” to only consider reputable practitioners and avoid the “Stem Cells are Us” style clinics.

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