The short version
Knee osteoarthritis ranges from mild cartilage thinning to complete loss of joint space with bone grinding on bone. Treatments that make sense at one stage may be pointless at another. Total knee replacement (TKR) is the most effective option for severe arthritis. Stem cell therapy and PRP are options some people consider for mild to moderate disease, especially if they want to delay surgery.
Side-by-side comparison
| Stem cell injection | Total knee replacement | |
|---|---|---|
| What it is | Injection of mesenchymal stromal cells into the joint | Surgery replacing damaged joint surfaces with metal and plastic |
| Best suited to | Mild to moderate osteoarthritis | Severe, end-stage osteoarthritis |
| Evidence | Moderate, mixed; some trials show pain and function benefit | Strong; decades of data and large registries |
| Invasiveness | Needle injection, usually local anaesthetic | Major surgery, anaesthetic, hospital stay |
| Recovery | Walking same day; reduced activity for days to weeks | Weeks to months of rehabilitation |
| Main risks | Pain flare, swelling, rare infection | Infection, blood clots, stiffness, persistent pain in a minority, revision surgery |
| Approval status (US/UK/AU) | Not approved outside trials | Standard care |
| Rebuilds the joint? | No consistent evidence of cartilage regrowth | Replaces joint surfaces |
The NHS has a clear guide to knee replacement, including recovery and risks.
What the evidence says about stem cells for knees
Randomised trials and meta-analyses of mesenchymal stem cell injections in knee osteoarthritis report improvements in pain and function in some patients, but study quality and results vary and some trials show results similar to comparison treatments. PubMed meta-analyses. Benefit, when seen, tends to be in symptoms rather than in clear structural repair.
Other alternatives to knee replacement
| Option | Notes |
|---|---|
| Exercise therapy and physiotherapy | First-line; proven to reduce pain and improve function |
| Weight loss | Reduces load on the knee; meaningful symptom benefit |
| Bracing and walking aids | Helpful for some patterns of arthritis |
| Steroid injection | Short-term relief, often weeks |
| Hyaluronic acid | Mixed evidence |
| PRP injection | Mixed evidence; compare in stem cells vs PRP |
| Genicular nerve radiofrequency ablation or artery embolisation | Newer procedures for pain; growing evidence |
| High tibial osteotomy | Surgery for younger patients with one-sided arthritis |
| Partial knee replacement | For arthritis limited to one compartment |
Who may be better suited to stem cells or PRP?
- Imaging shows mild to moderate change (often Kellgren-Lawrence grade 2 to 3).
- Pain is affecting life despite exercise therapy and weight management.
- You want to delay surgery or are not yet a surgical candidate.
- You accept that the benefit is uncertain and may be temporary.
Who may be better suited to knee replacement?
- Severe arthritis with bone-on-bone contact, deformity or instability.
- Pain at rest or at night that has not responded to other treatment.
- Significant loss of function and quality of life.
- You are fit enough for surgery and rehabilitation.
If your imaging shows severe disease, we will tell you that surgery is likely to be the more effective option and suggest you discuss it with an orthopaedic surgeon.
Risks of each option
Knee injections with PRP or cells commonly cause a pain flare and swelling for a few days; infection is rare but serious. Their main drawback is uncertain benefit, especially in advanced arthritis. Knee replacement is an effective operation, but carries the risks of major surgery, including infection, blood clots, stiffness, persistent pain in a minority and, years later, possible revision surgery. The NHS lists these knee replacement risks.
How to find out which applies to you
- Send your knee X-ray or MRI and any reports on WhatsApp.
- A doctor reviews the stage of arthritis and your history.
- You receive honest advice: conventional care, a regenerative program, or a surgical opinion.
Cells are prepared in ISO 9001:2015-certified partner laboratories, and injections are performed under image guidance by Thai Medical Council-licensed doctors. Read how it works.
Related: meniscus tear, hip osteoarthritis, rheumatoid arthritis.
Frequently asked questions
Can stem cells replace knee replacement surgery?
Not for severe, bone-on-bone arthritis with deformity. For mild to moderate osteoarthritis, stem cell injections may help some people delay surgery, but there is no guarantee and evidence is mixed.
What are the latest alternatives to knee replacement?
Options include exercise therapy, weight loss, bracing, injections (steroid, hyaluronic acid, PRP, stem cells), genicular nerve ablation or embolisation, and in selected people osteotomy or partial knee replacement.
Am I too old for stem cell knee treatment?
Age alone is not the deciding factor. The stage of arthritis on imaging, overall health and goals matter more. Send your X-ray or MRI for a doctor review.
How long does a knee replacement last?
Most modern knee replacements last many years; large registry studies show the majority still functioning at 15 to 20 years. Recovery takes weeks to months.
Can I have stem cells if I may need a knee replacement later?
Generally yes. Injections do not usually prevent later surgery. Tell your surgeon about any injections, as timing between injections and surgery matters for infection risk.
This page is general information, not medical advice, and does not replace a consultation with your own doctor. Results vary and no treatment outcome can be guaranteed. We are a patient coordination service and may receive a referral fee from partner medical providers. See our medical disclaimer and referral disclosure.