Knee osteoarthritis is wear and inflammation of the knee joint, where the smooth cartilage thins and the joint becomes painful and stiff. It is one of the most common causes of disability in people over 50. Researchers are testing mesenchymal stromal (“stem”) cells because in the lab they calm inflammation and send signals that may support repair, though they do not appear to regrow cartilage reliably.
AT A GLANCE · KNEE ARTHRITIS
| Evidence level | Promising – in clinical trials |
|---|---|
| Approved stem cell treatment? | No stem cell product is approved by the US FDA or the EU’s EMA for knee arthritis; the FDA lists arthritis among conditions for which no regenerative product is approved. |
| Typical private price | $1,150 – $12,000 (indicative) |
| Recruiting trials | 22 listed on ClinicalTrials.gov (4 October 2026) |
| Last reviewed | October 2026 |
Does stem cell therapy work for knee arthritis?
Knee arthritis is the most-studied use of stem cell injections, with many small randomised controlled trials (RCTs). Several 2024–2025 meta-analyses of RCTs report modest improvements in pain and function compared with placebo or hyaluronic acid at 6–12 months. However, a 2025 meta-analysis of 8 placebo-controlled RCTs (467 patients) found that roughly half to two-thirds of the improvement people felt came from placebo and other ‘contextual’ effects, with the cells adding only a small extra benefit; certainty of evidence was rated low.
Evidence that injections regrow cartilage on scans is weak and inconsistent. Trials differ widely in cell source (bone marrow, fat, umbilical cord), dose and preparation, and most are small and short. The American College of Rheumatology strongly recommended against stem cell injections for knee and hip osteoarthritis in its 2019 guideline and again in 2026. Large, long-term, well-blinded trials are still needed.
Is any stem cell treatment approved for knee arthritis?
No stem cell product is approved by the US FDA or the EU’s EMA for knee arthritis; the FDA lists arthritis among conditions for which no regenerative product is approved. South Korea approved an allogeneic (donor) umbilical cord blood-derived stem cell product, implanted surgically for cartilage defects in knee osteoarthritis, in 2012, and that product entered a US phase 3 trial in 2026. Clinic injections of bone marrow concentrate or fat-derived cells in the US are not FDA-approved treatments for arthritis.
What private clinics offer — and how it compares
Private clinics commonly sell one-off injections of bone marrow concentrate, fat-derived cells, or birth-tissue (amniotic or umbilical) products, often marketed as ‘regrowing cartilage’ or helping people ‘avoid knee replacement’. The best trials show small, short-term pain benefits at most, no reliable cartilage regrowth, and no proof that injections delay joint replacement.
Proven treatments to discuss first
Before paying for an experimental option, make sure you have explored the established treatments for knee arthritis with your doctor:
- Structured exercise and physiotherapy (strongly recommended)
- Weight loss if overweight
- Oral or topical anti-inflammatory medicines (NSAIDs)
- Corticosteroid (steroid) joint injections for flare-ups
- Braces, walking aids and activity changes
- Partial or total knee replacement for severe arthritis
How much does stem cell therapy for knee arthritis cost?
Private clinics typically quote $1,150 to $12,000. A US secret-shopper survey of 65 clinics presented at the AAOS annual meeting found knee stem cell injections averaged $5,156, ranging from about $1,150 to $12,000. A 2021 UC Irvine study found an average of about $5,100 per treatment across US clinics; insurance usually does not pay. Compare prices by country in our cost guide and location guides, and check insurance coverage.
Risks and side effects
- Pain, swelling and stiffness in the knee for days after injection
- Joint or harvest-site infection; the FDA has received reports of serious infections after unapproved cell products
- Pain, bruising or rare nerve injury at the bone marrow or fat harvest site
- Contaminated or poorly made products from unregulated labs
- Spending thousands of dollars and delaying proven treatments such as physiotherapy or surgery
Recruiting clinical trials for knee arthritis
On 4 October 2026, ClinicalTrials.gov listed 22 recruiting or soon-to-recruit stem cell studies for this condition, 5 with sites in the United States. Here are up to eight, latest-stage first:
See all matching studies on ClinicalTrials.gov. A listing is not an endorsement: registration does not mean a study is safe or effective, and genuine trials rarely charge you for the experimental treatment. Ask the study team about costs, placebo groups and follow-up before you enrol. See our clinical trials hub.
Questions to ask before you agree to treatment
- What exactly is being injected, where do the cells come from, and how is the product processed?
- What published randomised trials support this for my stage of knee arthritis?
- Is this part of a registered clinical trial with independent oversight?
- What should I do if my knee becomes hot, swollen or more painful afterwards, and who pays for complications?
Before You Pay: The Stem Cell Clinic Checklist
- 20 questions every legitimate clinic should answer in writing
- A red-flag scorecard to spot unregulated marketing
- Realistic 2026 cost ranges: US, Mexico, Panama & Europe
- How to find a registered clinical trial
Red flags to watch for
- Promises to ‘regrow cartilage’ or guarantee you can avoid knee replacement
- Before-and-after X-rays or MRI ‘proof’ from single patients instead of published trial results
- Pressure to treat both knees or buy a multi-injection package paid up front
Stem cell therapy for knee arthritis: FAQs
Does stem cell therapy work for knee arthritis?
Trials suggest stem cell injections may give a small improvement in pain and function for some people, but a 2025 analysis found most of the benefit comes from the placebo effect. There is no reliable evidence they regrow cartilage. Major guidelines, including the American College of Rheumatology in 2026, recommend against them.
How much does a stem cell knee injection cost?
US surveys found an average price of about $5,100–$5,200 per treatment, with quotes ranging from around $1,150 to $12,000 per knee. Prices are usually paid out of pocket and may not include imaging or follow-up visits.
Is stem cell therapy FDA approved for knee arthritis?
No. The FDA has not approved any stem cell product for arthritis and warns patients about unapproved clinics. South Korea approved one donor cord blood-derived cartilage product in 2012, and it is still being tested in a US trial.
How long does a stem cell knee injection last?
Most trials follow patients for only 6–24 months, and any benefit seen tends to be modest. There is no good evidence that results last for years or that injections delay knee replacement.
Is stem cell therapy for knees covered by insurance?
Usually not. US insurers generally treat stem cell injections for orthopaedic problems as investigational, so patients normally pay the full cost themselves.
Related guides
- Stem cell therapy for back pain
- Stem cell therapy for rotator cuff tears
- Stem cell therapy for hip arthritis
- Stem cell therapy for sports injuries
- All conditions · Types of stem cell treatment · Clinical trials hub
Sources
- American College of Rheumatology – 2026 Osteoarthritis Guideline Summary
- ACR / Arthritis Foundation 2019 osteoarthritis guideline press release
- Contextual effects of MSC injections for knee osteoarthritis: systematic review and meta-analysis of RCTs (Frontiers in Medicine, 2025)
- Efficacy and safety of mesenchymal stem cells in knee osteoarthritis: systematic review and meta-analysis of RCTs (2025)
- Single versus repeated MSC injections for knee osteoarthritis: network meta-analysis of RCTs (Stem Cell Research & Therapy, 2025)
- AAOS – Management of Osteoarthritis of the Knee (Non-Arthroplasty) Clinical Practice Guideline (2021)
- A Brief Overview of Global Trends in MSC-Based Cell Therapy (review; notes Korea’s 2012 approval)
- Allogeneic cord blood-derived MSC implantation vs microfracture for large cartilage defects: multicentre RCT with 5-year follow-up (2021)
- FDA – Important Patient and Consumer Information About Regenerative Medicine Therapies
- UC Irvine (2021) – Businesses selling non-FDA-approved stem cell products grew four-fold in five years
Last reviewed October 2026. For general information only — not medical advice. We do not endorse any clinic or product. Always consult a qualified, licensed healthcare professional. See our medical disclaimer and editorial policy.