Stem Cells for Knee Osteoarthritis: Evidence and Cost

Short answer: Reviews of randomized trials disagree on whether stem cell injections do anything measurable for knee osteoarthritis. A 2024 review found probably little to no difference in pain or function, and a 2025 review found improvements on WOMAC, VAS and KOOS. Published Bangkok prices for knee stem cell treatment run from $1,600 to $4,500 across two third-party sites; Bookimed does not say whether its figure is per knee. According to a lawsuit reported by Nation Thailand in December 2024, the Medical Council warned at an October 31 press conference that treating conditions outside blood or eye diseases with stem cells could be unlawful.

This guide is general information for someone weighing a trip. It describes what published studies measured. It does not say what any treatment will do for you.

What the procedure is

Osteoarthritis is wear in the joint. The procedures sold as "stem cell therapy" for it are often injections of mesenchymal stem cells (MSCs) into the knee joint, although some clinics use other cell preparations. Stemcierge, a site about regenerative medicine in Thailand, says the cells can come from your own bone marrow or fat tissue, which may need to be harvested and processed first, or from a donor. It says the cells may be given in an ultrasound-guided joint injection, and that some clinics expand cells in a laboratory to reach a larger number.

A stem cell injection is not a knee replacement. A knee replacement is surgery that replaces the damaged joint surfaces. OrthoInfo says that if nonsurgical treatments like medications and walking supports are no longer helpful, a person may want to consider total knee replacement surgery. When people search for "stem cell knee replacement," they are comparing two different things.

What the evidence shows, and what it does not

The 2024 review. Sadeghirad and colleagues searched four databases up to September 2023 and pooled 16 randomized trials with 807 participants, comparing MSC injections with placebo or usual care (Osteoarthritis and Cartilage, 2024). At 3 to 6 months, pain on a 10 cm scale was 0.74 cm lower with MSCs on average, against a minimally important difference the authors set at 1.5 cm. Physical function on the SF-36 differed by 2.23 points on a 100-point scale, against a minimally important difference of 10 points. At 12 months, pain differed by 0.73 cm, and the confidence interval included no difference. At 12 months the authors said MSCs may improve physical function (19.36 points on the SF-36 scale, confidence interval -0.19 to 38.9, low certainty). They rated the certainty moderate for the pain results and for function at 3 to 6 months, and concluded that MSC injection "probably provides little to no improvement in pain or physical function."

The 2025 review. Cao and colleagues (Stem Cell Research and Therapy, 2025) pooled 8 randomized trials with 502 people who had not had knee surgery. They reported better WOMAC scores (a standard knee questionnaire) at 6 months, by a mean of 7.44 points, and at 12 months, by 10.31 points, compared with the control groups. They also reported improvements on VAS and KOOS at 6 and 12 months, and, in a subgroup comparison, a larger effect with fat-derived cells and higher doses; the abstract of the 2024 review does not report this comparison. They found no significant difference in adverse events. The abstract says the quality of the trials was evaluated but gives no quality rating for the evidence.

Why they differ. The two reviews included different sets of trials and used different outcome scales. As far as their abstracts show, the 2024 team compared the results with a minimally important difference, while the 2025 paper reports statistical differences. That is our reading, and we cannot tell you which review is right. What both show is that trials vary in cell source, dose and control treatment, so a single "success rate" would hide more than it shows.

No success rate from us. We do not quote a success percentage. Some commercial pages publish clinic-reported rates. The abstracts of the reviews above do not report a comparable figure.

Stemcierge itself says the evidence on knee osteoarthritis "remains mixed." The US FDA says, in its public information on regenerative medicine therapies (3 June 2021), that unapproved stem cell products require FDA oversight in a clinical trial before marketing. That is a US rule, but it is a useful test of any offer: is it inside a trial with oversight, or not?

Established alternatives

The 2019 American College of Rheumatology and Arthritis Foundation guideline made strong recommendations for exercise, losing weight for people who are overweight or obese, self-management programs, tai chi, bracing of the tibiofemoral joint, topical and oral NSAIDs, and injections of glucocorticoids (steroids) into the knee. It made conditional recommendations for several other options, including acupuncture, heat, and radiofrequency ablation. For severe damage, OrthoInfo describes total knee replacement and says serious complications such as joint infection occur in fewer than 2 percent of patients. Our guide PRP vs stem cell therapy covers a related injection, and its evidence is also mixed.

Who may be a poor candidate

The abstracts we reviewed do not say who should be excluded from a stem cell injection. Ask your own doctor first, especially if you have an active infection, a cancer history, a bleeding disorder, take blood thinners or are pregnant. These are our prompts, not exclusion rules from the cited studies. The 2025 review looked only at people who had not had knee surgery, so it tells you nothing about people who had. A doctor who knows your history is the person to ask, and you should ask before you travel.

Risks

The HSS Journal review (Riggle and colleagues) covered 48 studies with 1,924 patients who had stem cell-based injections for knee osteoarthritis. It found transient adverse events in 12.3 percent, most often swelling and pain at the injection site, lasting under 4 weeks. Rates were higher after umbilical cord-derived cells (51.7 percent) and cultured fat-derived cells (29.5 percent) than after bone marrow cells or stromal vascular fraction. It found no reports of infection or fat embolism in the included studies, which varied widely in protocol, formulation, timing and location of injections. It called for long-term studies.

The 2024 meta-analysis reached a less comfortable result: MSC therapy may increase the risk of any adverse event (risk ratio 2.67, low certainty) and of pain and swelling in the joint (risk ratio 1.58, low certainty).

The FDA's 2021 page says it has received reports of blindness, tumor formation and infections linked to unapproved regenerative medicine products. The FDA page does not say where these reports came from or which body sites were involved. It covers unapproved regenerative products in general, not knee injections in Thailand specifically.

Published Bangkok prices

We have no prices from any clinic. These are figures published by third parties. We last checked them on 4 November 2026.

The two sites do not line up, and we cannot tell from their pages whether they price the same cell product and dose. Stemcierge says one clinic may quote about $3,000 for a knee injection while another recommends a package of about $23,900 with infusions, testing and rehabilitation. Flights, extra hotel nights and treatment of complications may not be included unless the quote says so in writing. Our cost guide lists the rest.

Thai legal status

Knee osteoarthritis is not a blood or eye disease. In December 2024, Nation Thailand reported a lawsuit by a group of doctors against the Medical Council of Thailand. The report cites a press conference at which the Council warned that treating conditions outside of blood or eye diseases with stem cells could be unlawful.

Nation Thailand also reported, on 27 May 2026, a ministerial decree that classifies cell products with "more than minimal manipulation," such as cells expanded in culture or enzymatically digested, as medicines that need registration with the Thai FDA. Whether a particular offer is lawful is a question for a Thai lawyer or the clinic's written answer. This guide is not legal advice. Our guide Is stem cell therapy legal in Thailand? has the full set of facts and sources.

Five questions to ask a clinic

• Is this treatment part of a regulated clinical trial with ethics committee approval, or is it offered outside one?
• Is the cell product registered with the Thai FDA, and for which condition?
• What is the source of the cells, how many are in the dose, and are they only cut, spun or separated, or cultured, enzyme-treated or otherwise processed further?
• What published studies support this use for knee osteoarthritis, and what did they measure?
• What is included in the price, and who pays and where do I get care if I have a complication after I fly home?