Are Umbilical Cord Stem Cells Better for Knee Cartilage Repair?

Medical inforgrapic showing a bone marrow aspiration including a close-up of the needle in the bone marrow


Let’s look today at two studies that posit an interesting question. They both ask if umbilical cord stem cells are better than the patient’s own bone marrow concentrate in healing a small cartilage lesion in the knee. This is an important topic because we have hundreds of crazy chiropractic clinics claiming that they are injecting umbilical cord “stem cells”, but are really offering dead cells. Let’s dig in.

These Studies DID NOT Use Umbilical Cord “Stem Cells” that Are Sold Here in the USA

Before I get into these two studies, it’s critical for everyone to understand that the isolated and culture-expanded umbilical cord stem cells in these studies have no resemblance to the products being sold in the US which are whole tissues that have no living and functional mesenchymal stem cells. They are apples and oranges. Hence, nothing written here should be used to support the idea that dead birth tissue products used in many chiropractic and alternative health clinics have any impact on knee cartilage lesions. On the other hand, the other substance used in these studies, bone marrow concentrate, is used commonly here in the U.S. This is created by centrifuging bone marrow obtained from the patient’s iliac crest.

To directly answer the question about Signature Cord (the US sold umbilical cord tissue product) in the comments, the data collected to date DOES NOT support that this product has live and functional mesenchymal stem cells. That includes any other product sold in the US today that is derived from umbilical cords and is claiming to have millions of live and functional stem cells. See my video below for more information:

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What Surgeries Are Being Discussed Here?

This blog discusses several surgeries:

  • Microfracture – Used only to treat small potholes in the cartilage. This is when the doctor pokes holes in the bone to try to stimulate cartilage growth.
  • HTO-High Tibial Osteotomy – This is only performed in patients who have a significant side bend to the knee (i.e. valgus). This is a procedure where the doctor cuts out a wedge of bone to straighten the knee and then adds a plate to hold the area together while it heals.

Study 1-Umbilical Cord Stem Cells Are No Better than Bone Marrow Concentrate

The first study used patients with a pothole in the cartilage where they performed a microfracture surgery (2). One group got culture-expanded umbilical cord blood mesenchymal stem cells and the other got bone marrow concentrate. Two years later, both groups had the same pain and function improvements after the two different procedures. In addition, high-definition MRI also showed no difference in the healing of the cartilage.

Study 2-Umbilical Cord Cells are Maybe Better?

The second study used the same two groups – umbilical cord mesenchymal stem cells and bone marrow concentrate. The second study also performed microfracture on everyone and also added in a high-tibial osteotomy surgery. The follow-up was shorter at about 18 months and there was also no difference in the clinical outcomes. However, instead of an MRI to follow-up the structure of the cartilage lesion, there was a second surgery to remove the plate from the HTO, so they performed a second arthroscopy to look at the status of the lesion. In this study, they stated they saw better cartilage in the umbilical cord group.

Analyzing Two Studies with Different Outcomes

Science and medicine is full of studies that conclude opposite things. Hence, it’s our job to see what’s up. How were the studies different? Does one carry more weight than another?

Retrospective Studies

Both of these studies are backward-looking, meaning that they are retrospective. Hence neither is the gold standard randomized controlled trial. So we have no idea what would happen if we used these therapies in that better study design.

Different Follow-up Periods

The first study followed the patients for two years and the second for about 18 months. The gold standard for knee intervention studies tends to be two years, so the second study loses a few brownie points.

Different Patient Populations

The first study used normally aligned knees with a pothole in the cartilage whereas the second used patients with knees that had a side bend. Hence, they were similar, but different diagnoses. These differences in the patients treated may be why different results were seen.

Different Cartilage Grading Techniques

The first study used MRI to grade the quality of the cartilage repair and the second used arthroscopy. Each has its advantages and disadvantages. MRI allows us to see what’s happening in the cartilage and bone, whereas arthroscopy can’t show the bone reaction part of the pothole. Arthroscopy can be more accurate for looking at the surface characteristics of the cartilage.

Important Caveat

Neither of these studies included patients with moderate or severe bone-on-bone arthritis! These were mild arthritis cases where there was a small hole in the cartilage. While repairing small cartilage holes is easier (we’ve done it with just a precise image-guided injection of stem cells-see my video below), repairing the cartilage when there is more severe cartilage loss doesn’t happen with either of these procedures.

The upshot? Neither of these studies can definitively answer the question of whether bone marrow stem cells repair small holes in the cartilage as well as umbilical cord stem cells.  To get there will take a randomized controlled trial where patients who are the same are assigned to one treatment or the other and then the same imaging technology is used to see what happened. In the meantime, I always look forward to more research!



(1) van den Borne MP, Raijmakers NJ, Vanlauwe J, Victor J, de Jong SN, Bellemans J, Saris DB; International Cartilage Repair Society. International Cartilage Repair Society (ICRS) and Oswestry macroscopic cartilage evaluation scores validated for use in Autologous Chondrocyte Implantation (ACI) and microfracture. Osteoarthritis Cartilage. 2007 Dec;15(12):1397-402. doi: 10.1016/j.joca.2007.05.005. Epub 2007 Jul 2. PMID: 17604187.

(2) Ryu DJ, Jeon YS, Park JS, Bae GC, Kim JS, Kim MK. Comparison of Bone Marrow Aspirate Concentrate and Allogenic Human Umbilical Cord Blood Derived Mesenchymal Stem Cell Implantation on Chondral Defect of Knee: Assessment of Clinical and Magnetic Resonance Imaging Outcomes at 2-Year Follow-Up. Cell Transplant. 2020 Jan-Dec;29:963689720943581. doi: 10.1177/0963689720943581. PMID: 32713192; PMCID: PMC7563925.

(3) Lee NH, Na SM, Ahn HW, Kang JK, Seon JK, Song EK. Allogenic Human Umbilical Cord Blood-derived Mesenchymal Stem Cells is more effective than Bone Marrow Aspiration Concentrate for cartilage regeneration after High Tibial Osteotomy in Medial Unicompartmental Osteoarthritis of Knee. Arthroscopy. 2021 Feb 20:S0749-8063(21)00155-9. doi: 10.1016/j.arthro.2021.02.022. Epub ahead of print. PMID: 33621649.

Chris Centeno, MD is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. View Profile

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NOTE: This blog post provides general information to help the reader better understand regenerative medicine, musculoskeletal health, and related subjects. All content provided in this blog, website, or any linked materials, including text, graphics, images, patient profiles, outcomes, and information, are not intended and should not be considered or used as a substitute for medical advice, diagnosis, or treatment. Please always consult with a professional and certified healthcare provider to discuss if a treatment is right for you.