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Outcomes, Complication Rates, and Stem Cell Procedures

POSTED ON IN Knee Latest News BY Chris Centeno

stem cell procedure complications

Given the quite reasonable concerns this past week over the blinding of three women by a stem cell clinic injecting fat stem cells into eyes, I thought it was time to take a look at stem-cell-procedure complications. All medical procedures have complications. So what bar can we use to see if those complications are reasonable, and how should those be reported and measured?

Every Procedure Has Complications, and Every Medication Has Side Effects

First, to decide what complications might be reasonable, we need to understand the playing field of common side effects of conventional treatments. So what are some common complications in my world of orthopedic care, and how often do they happen?

So conventional procedures and widely used medications can have big time complications and rates!

Reported Complication Rates for Stem Cell Procedures

To date, I think we’ve reported the most comprehensive paper on stem-cell-related complications. In more than 2,300 patients and 3,000 procedures, the total complication rate was 2.0%. Of those, four were deemed to be more serious and definitely related to the procedure by at least one independent reviewer not related to our group. Since this is out of 3.012, this is a serious-complication rate of 0.13%. Pretty small compared to the rates reported above for common orthopedic procedures.

This week we saw reported that the complication rate for the fat stem cell clinic that blinded three consecutive patients was approximately 0.01%. That seems about ten times less, despite the significant reported complications. Why? The data is an apples to oranges comparison.

For our reported data, a registry infrastructure was used where questionnaires were sent to every patient, and if they failed to respond, telephone calls were made. Based on conversations I have had with participating physicians, the stem cell outfit with the complications uses a passive system where the doctors are told to report the complications. It’s likely that pinging patients about what’s wrong can find more complications when compared to relying on a busy physician to report his or her complications.

Regrettably, the stem cell outfit that blinded these patients hasn’t published any safety data on the widespread use of fat stem cells, so there is no research to review. This is concerning.

The Risk of Stem Cell Procedures vs. Traditional Care

As you can see from the above risks, stem-cell-based orthopedic therapies have low-risk profiles when compared to conventional orthopedic procedures. Hence, when complications do occur, they are rare. However, to determine risk, efficacy is also needed as part of the calculus. So let’s look at knee replacement.

So how “good” is knee replacement compared to garden-variety physical therapy (PT)? Not great. In a recent study (video below), 3 in 4 knee-replacement candidates undergoing PT instead of surgery decided not get a knee replacement after one year. Also you need to amputate 5–6 knees to find just one patient who reports more than a 15% functional improvement as a result of this maximally invasive surgery.

Looking at the relative efficacy of two procedures is hard without a head-to-head comparison trial. However, in the case of knee arthritis, we can compare two different studies that both compare to PT. In the above case of knee replacement, we know how that invasive procedure fared, and below we’ll look at a same-day stem cell procedure.

For the stem cell procedure, we’ll be looking at the Regenexx bone-marrow-based version. Below is a graphic that discusses that out of more than 5,000 knee stem-cell-treated patients, as of this month, only about 12% went on to get a knee replacement despite their treatment at 1–2 years. This was based on 100% response rate from a random sample of 100 registry patients.

Below are the yet unpublished results of our randomized controlled trial where knee-replacement candidates were treated with our Regenexx knee stem cell procedure versus physical therapy:

The patients with a stem cell procedure report more knee function more quickly compared to the physical therapy group (listed here as “Exercise Therapy”). The PT group crossed over to the stem cell procedure at three months, which is why the PT data is only tracked for that long.

So comparing risks and benefits of these two therapies, the risk of knee replacement is significantly greater and the outcome based on a randomized controlled trial is likely no better than a stem cell injection. Hence, the risk/benefit of a Regenexx-protocol knee stem cell procedure is good compared to traditional care.

The upshot? While the risks of stem cell therapy are likely lower than most traditional treatments, for some indications, like injecting fat stem cells in the eye, that equation goes in the wrong direction. The goal with today’s review was also to open a debate about when stem cell therapy is likely the better option. So let’s have a reasonable discussion about stem cell risks and not throw the baby out with the bathwater!


    Sandy Rozelman says

    I had stem cell treatment on my hip and knee at Hillcrest Hospital in Cleveland, OH in July 2016. To date, I am seeing vast improvement in pain and mobility in my knee (about 95%) and about 80% improvement in my hip mobility. I'd say that this treatment was extremely successful. If not for the cost not covered by insurance, I would be doing my shoulder and maybe my back as well. I hope it will be covered soon.


    Chris Centeno says

    Really glad to hear that!


    julienne johnson says

    Is stem cell replacement a possibility on the hands? Specifically the thumb area when caused by osteoarthritis? Both thumbs are messed up, but particularly, my right hand is just bone rubbing bone. I am a visual artist that uses her hands for painting, sculpture and drawing. Glucosamine keeps the pain to a minimum and wearing gloves 10 out of 12 months a year for morning power walking additionally helps.
    Thank you,
    Julienne Johnson


    Chris Centeno says

    Yes, CMC and thumb arthritis are things we treat regularly. Please see: and


    joan mcarthur says

    1)How about knees that have a replacement and are again causing great pain?
    2) and treatment for lumbar L-4,L-5 areas where is it bone on bone?

    Thank you.


    Chris Centeno says

    Unfortunately, low back issues can be a predictor of poor knee replacement outcome. With the knee joint gone, there is nothing we can do for the knee itself, but treating your back, which operates the nerves, muscles and ligaments controlling your knee, may improve things. If you'd like to see if you'd be a candidate, please submit the Candidate form. Please see:


    Michael Cavalieri says

    I have illioinguinal and illiohypogastric nerve entrapment. My entire area innervated by these nerves is numb. Can you guys help break up the scar tissue in the area with Regenexx?


    Chris Centeno says

    This is very specialized treatment that can be done at a handful of Regenexx locations. If you are interested in doing that, please let us know and we can assist in getting you set up.


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    About the Author

    Chris Centeno

    Christopher J. Centeno, M.D. is an international expert and specialist in regenerative medicine and the clinical use of mesenchymal stem cells in orthopedics. He is board certified in physical medicine as well as rehabilitation and in pain management through The American Board of Physical Medicine and Rehabilitation.…

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