Stem Cell Knee Procedures: Are They Worth It?


Pioneer Founding member
Regenexx Blog
Stem Cell Knee Procedures: Are They Worth It?
By Chris Centeno, MD / August 25, 2019

Click for graphics, video, and embedded links:

You can’t turn around these days without seeing an ad for miracle stem cell knee injections. However, these ads bring up many questions. Does stem cell therapy work for knees? Can stem cells repair knee cartilage? Is stem cell therapy for knees covered by insurance? How long does stem cell therapy last for knees?

The Idea Behind Stem Cell Knee Injections
Patients with moderate to severe knee arthritis are generally knee replacement candidates. In one 2006 study, it was estimated that at that time, approximately 700,000 knee replacement surgeries were completed per year in the U.S. (1). This number was projected to explode to roughly 3.5 million operations annually by 2030!

This is a big surgery which involves the amputation of the existing joint and then the insertion of a knee replacement device. The complications can include (this is a short list): blood clots, infection, heart attack, stroke, and increased chronic pain (2). Despite this being a common procedure, you might be startled to learn that a recent large study demonstrated that in many patients the procedure didn’t work all that well (3). The problem? Younger and more active patients are more likely to be dissatisfied with the results.

The idea behind stem cell knee procedures is that a much less invasive injection may be able to get rid of the need for a knee replacement or push that surgery back until the patient is older. However, is there any science that shows this works? If so, what type of stem cell knee procedures probably work?

Does Stem Cell Therapy Work for Knees?
While there are wild claims out there, the only way to see if these knee stem cell procedures are worth the money is to perform a quick, but deep dive into whether we have research showing that they work. The first publications on stem cell knee injection procedures were actually by our group in 2008 using bone marrow stem cells (4,5). We then followed up with a few more studies showing that bone marrow concentrate produced good results for knee arthritis patients and tested various doses and if adding a fat injection helped (6,7). We later performed a randomized controlled trial using this same day, bone marrow based injection treatment for knee arthritis (8).

Others have published research as well. Recently a university group published on whether the Lipogems fat system produced better results than bone marrow concentrate and found that they worked about the same (9). Other technologies like cultured bone marrow cells (grown in a lab to bigger numbers) also show promise in treating knee arthritis, but none of these has US FDA approval at this time (10-12). Suffice it to say that much research is being done in this area both on same-day and cultured procedures.

What Are the Different Types of Stem Cell Knee Procedures?
Knee stem cell procedures can be broken down into two main types:

Autologous means your own cells. There are two types of autologous knee stem cell procedures:

Bone marrow
By far, the most popular type of treatment that uses your cells is bone marrow. This involves taking a sample of bone marrow aspirate (looks like thick blood) and then centrifuging that to get the stem cell fraction out. What results is called bone marrow concentrate (BMC or BMAC). Some clinics cut corners by skipping the centrifuge step, as it saves the doctor time, but reduces the number of stem cells harvested.

Fat is another common choice. In this case, a liposuction procedure is performed to harvest tissue for processing. One problem is that the stem cells in fat are locked in collagen and must be digested to free them for use. This digestion step is not legal in the U.S. but is compliant in most of Europe and elsewhere. In the U.S. the most common fat procedure involves breaking down the fat into small pieces and is called “Micro fat” (aka Lipogems). There’s mounting evidence that this can help knee arthritis, although this is not really a stem cell procedure.

Allogeneic means cells from someone else. The most common types of treatments here are derived from amniotic or umbilical cord blood. These products are taken from live cesarian births. More on them below.

A Word of Caution on Amniotic and Umbilical Cord “Stem Cells”
If you attend a seminar on stem cells these days, you’re bound to hear that your stem cells are too old and this means that you need to use stem cells from amniotic or umbilical cord tissue which are young and plentiful. Regrettably, none of that is true, as multiple researchers have tested the amniotic and umbilical cord products these clinics use and none has any live stem cells (16-18). In fact, your own bone marrow has far more stem cells than these birth tissue products.

If you want to dive deeper on this topic of birth tissues, see my video below:

ProPublica also wrote a good piece on this topic called, The Birth Tissue Profiteers.

Can Stem Cells Repair Knee Cartilage?
This is a question with a few answers. First, in selected patients with small holes in their cartilage, the answer is “Yes”. Meaning we and others have published on cartilage improvement as seen on MRI in patients with cartilage and meniscus lesions (4,5,13). However, for the next obvious questions, it all gets a bit more complex. For instance, if you have some cartilage left, can stem cell injections improve that cartilage quality? Likely. For example, several studies in actual patients have shown improved cartilage quality with the injection or surgical implantation of fat tissue and bone marrow concentrate (14,15). On the final question of whether knee stem cell injections can regrow cartilage in “bone on bone” knees, the answer here is a clear and resounding “No”. No research reports that this is possible. Having said that, this is despite being able to see these same bone on bone knee arthritis patients respond to these treatments and report better pain and function.

To see what’s possible in cartilage regeneration in the knee with a bone marrow stem cell procedure, see my video below (starts around 3:29):

Why Did You See an Ad or a Seminar Advertisement that Showed an Improvement in Bone on Bone Arthritis X-rays?
Regrettably, the x-ray results shown in these seminars pushing birth tissues aren’t real. All it takes to make an x-ray of the knee look like it has grown cartilage and has a wider joint space is altering the x-ray beam a few degrees. See below for a video that explains how that scam works:

Is Stem Cell Therapy for Knees Covered by Insurance?
The answer is “No” for most patients. Having said that, Regenexx has gotten coverage for millions of patients through their self-funded health plan, a program which is growing every month. This coverage is likely to improve over time given all of the research being published.

How Much Does Knee Stem Cell Therapy Cost?
We’re used to the adage that you get what you pay for. While you can find knee stem cell injections for as low as a few thousand dollars to as a high as ten thousand dollars or more, many times there isn’t a direct correlation between price and expertise or real versus fake stem cells. I wrote a whole article on how to determine the right price for what you’re getting and to help you avoid getting ripped off on knee stem cell treatment.

How Long Does Stem Cell Therapy Last for Knees?
I’ve already done an in-depth analysis of how long stem cell therapy lasts for knees. Suffice it to say that based on our extensive data collected, a same day bone marrow stem cell procedure can last for approximately 2-7 years on average. After that, the procedure is usually repeated.

How Can You Make Sure You Find the Right Clinic?
This isn’t like knee replacement, where there are doctors who are board-certified and fellowship-trained in how to perform these procedures. In fact, it’s the wild west right now. I wrote a little book to help you sort the wheat from the chaff:

stem cell clinic guide (click link at top of page)

The upshot? It’s a confusing mess out there of wild claims, but there are some clinics trying to do this right. In most cases, stem cell therapy for knees can help you avoid a knee replacement, but making sure you don’t get scammed isn’t easy. So I hope this article helps you figure out how to get the most for your money!



(1) Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007 Apr;89(4):780-5. DOI: 10.2106/JBJS.F.00222

(2) Healy WL, Della Valle CJ, Iorio R, et al. Complications of total knee arthroplasty: standardized list and definitions of the Knee Society. Clin Orthop Relat Res. 2013;471(1):215–220. doi:10.1007/s11999-012-2489-y

(3) Ferket Bart S, Feldman Zachary, Zhou Jing, Oei Edwin H, Bierma-Zeinstra Sita M A, Mazumdar Madhu et al. Impact of total knee replacement practice: cost effectiveness analysis of data from the Osteoarthritis Initiative BMJ 2017; 356 :j1131 doi:

(4) Centeno CJ, Busse D, Kisiday J, Keohan C, Freeman M, Karli D. Increased knee cartilage volume in degenerative joint disease using percutaneously implanted, autologous mesenchymal stem cells. Pain Physician. 2008 May-Jun;11(3):343-53.

(5) Centeno CJ1, Busse D, Kisiday J, Keohan C, Freeman M, Karli D. Regeneration of meniscus cartilage in a knee treated with percutaneously implanted autologous mesenchymal stem cells. Med Hypotheses. 2008 Dec;71(6):900-8. doi: 10.1016/j.mehy.2008.06.042

(6) Centeno C, Pitts J, Al-Sayegh H, Freeman M. Efficacy of autologous bone marrow concentrate for knee osteoarthritis with and without adipose graft. Biomed Res Int. 2014;2014:370621. doi:10.1155/2014/370621

(7) Centeno CJ, Al-Sayegh H, Bashir J, Goodyear S, Freeman MD. A dose response analysis of a specific bone marrow concentrate treatment protocol for knee osteoarthritis. BMC Musculoskelet Disord. 2015;16:258. Published 2015 Sep 18. doi:10.1186/s12891-015-0714-z

(8) Centeno C, Sheinkop M, Dodson E, et al. A specific protocol of autologous bone marrow concentrate and platelet products versus exercise therapy for symptomatic knee osteoarthritis: a randomized controlled trial with 2 year follow-up. J Transl Med. 2018;16(1):355. Published 2018 Dec 13. doi:10.1186/s12967-018-1736-8

(9) Mautner K1 Bowers R, Easley K, Fausel Z, Robinson R. Functional Outcomes Following Microfragmented Adipose Tissue Versus Bone Marrow Aspirate Concentrate Injections for Symptomatic Knee Osteoarthritis. Stem Cells Transl Med. 2019 Jul 21. doi: 10.1002/sctm.18-0285.

(10) Chahal J, Gómez-Aristizábal A, Shestopaloff K, et al. Bone Marrow Mesenchymal Stromal Cell Treatment in Patients with Osteoarthritis Results in Overall Improvement in Pain and Symptoms and Reduces Synovial Inflammation. Stem Cells Transl Med. 2019;8(8):746–757. doi:10.1002/sctm.18-0183

(11) Lee WS, Kim HJ, Kim KI, Kim GB, Jin W. Intra-Articular Injection of Autologous Adipose Tissue-Derived Mesenchymal Stem Cells for the Treatment of Knee Osteoarthritis: A Phase IIb, Randomized, Placebo-Controlled Clinical Trial. Stem Cells Transl Med. 2019;8(6):504–511. doi:10.1002/sctm.18-0122

(12) Emadedin M, Labibzadeh N, Liastani MG, Karimi A, Jaroughi N, Bolurieh T, Hosseini SE, Baharvand H, Aghdami N. Intra-articular implantation of autologous bone marrow-derived mesenchymal stromal cells to treat knee osteoarthritis: a randomized, triple-blind, placebo-controlled phase 1/2 clinical trial. Cytotherapy. 2018 Oct;20(10):1238-1246. doi: 10.1016/j.jcyt.2018.08.005.

(13) Vangsness CT Jr, Farr J, Boyd J, Dellaero DT, Mills CR, LeRoux-Williams M. Adult human mesenchymal stem cells delivered via intra-articular injection to the knee following partial medial meniscectomy: a randomized, double-blind, controlled study. J Bone Joint Surg Am. 2014 Jan 15;96(2):90-8. doi: 10.2106/JBJS.M.00058.

(14) Hudetz D, Borić I, Rod E, et al. The Effect of Intra-articular Injection of Autologous Microfragmented Fat Tissue on Proteoglycan Synthesis in Patients with Knee Osteoarthritis. Genes (Basel). 2017;8(10):270. Published 2017 Oct 13. doi:10.3390/genes8100270

(15) Krych AJ, Nawabi DH, Farshad-Amacker NA, Jones KJ, Maak TG, Potter HG, Williams RJ. Bone Marrow Concentrate Improves Early Cartilage Phase Maturation of a Scaffold Plug in the Knee: A Comparative Magnetic Resonance Imaging Analysis to Platelet-Rich Plasma and Control. Am J Sports Med. 2016 Jan;44(1):91-8. doi: 10.1177/0363546515609597.

(16) Berger D, Lyons N, Steinmetz, N. In Vitro Evaluation of Injectable, Placental Tissue-Derived Products for Interventional Orthopedics. Interventional Orthopedics Foundation Annual Meeting. Denver, 2015.

(17) Becktell L, Matuska A, Hon S, Delco M, Cole B, Fortier L. Proteomic analysis and cell viability of nine amnion-derived biologics. Orthopedic Research Society Annual Meeting, New Orleans, 2018.

(18) Panero, A, Hirahara, A., Andersen, W, Rothenberg J, Fierro, F. Are Amniotic Fluid Products Stem Cell Therapies? A Study of Amniotic Fluid Preparations for Mesenchymal Stem Cells With Bone Marrow Comparison. The American Journal of Sports Medicine, 2019 47(5), 1230–1235.