PRP and Stem Cell Injections for Knee Arthritis
Platelet-rich plasma and stem cell injections for knee arthritis — what the Australian guideline says about each, what they cost, why the claim of cartilage regrowth is not supported, and the questions to ask before paying.
These two treatments are grouped together because patients usually encounter them together, but the evidence positions are genuinely different and it matters to keep them apart.
- Platelet-rich plasma (PRP): the Australian guideline makes no recommendation either way, citing a lack of high-quality evidence.
- Stem cell therapy: the Australian guideline does not recommend offering it for knee osteoarthritis.
One is unsettled. The other has been assessed and advised against.
Platelet-rich plasma
Your blood is taken, spun in a centrifuge to concentrate the platelets, and the concentrate injected into the knee. Platelets carry growth factors involved in healing, and the rationale is that concentrating them in an arthritic joint promotes repair and reduces inflammation.
The evidence is genuinely mixed rather than uniformly negative. Some trials show benefit, some do not, and quality varies. A significant complication is that “PRP” is not one thing — platelet concentration, whether white cells are included, the spin protocol, the injection volume and the number of injections all differ between providers, and there is no standard. Trials are therefore not all testing the same treatment, which is part of why the evidence has failed to converge.
The honest summary: PRP may turn out to help some people with knee arthritis. It has not yet been shown to, well enough for a guideline to recommend it. If you try it, you are paying to participate in an unresolved question.
Stem cell therapy
A firmer position, and worth being direct about.
The Australian guideline does not recommend offering stem cell therapy for knee osteoarthritis, and reviews of international guidelines have found strong recommendations against it for both hip and knee.
The treatments sold under this name vary enormously — cells harvested from bone marrow or from fat, prepared in different ways, with little standardisation and often limited evidence that what is injected contains meaningful numbers of the cells being advertised.
It is also, consistently, the treatment marketed with the boldest claims and the highest prices. That combination — weakest guideline support, strongest promises, largest cost — is worth registering.
The regeneration claim
This is the part to be clearest about.
No treatment currently available has been shown to regrow cartilage or reverse established arthritis in a human knee. Not PRP, not stem cells, not gel injections, not anything else on the market.
If regeneration, reversal or “healing the joint” is being promised, that promise is ahead of the evidence. In Australia, advertising of regulated health services is not permitted to create unreasonable expectations of benefit, and claims of cartilage regrowth sit squarely in that territory.
This is not a reason to distrust everyone offering these treatments. It is a reason to treat the specific claim of regeneration as a signal about the person making it.
What it costs
Both are generally out of pocket, and neither is typically covered by Medicare for knee osteoarthritis.
PRP commonly runs to several hundred dollars per injection and is often recommended as a course of three. Stem cell treatments are usually considerably more, sometimes several thousand.
Ask for the total cost of the complete recommended course, not the per-injection price.
The real risk is not medical
The direct risks of both are relatively low. Most problems are local — pain or swelling after injection — and serious complications are uncommon.
The more realistic harms are financial, and the opportunity cost: months spent on an unproven treatment, and a substantial sum spent, while the two things with strong evidence behind them go undone. A course of stem cell injections costs more than a year of supervised exercise physiology, which is the comparison worth holding in mind.
Questions worth asking
- What is this expected to achieve, and on what evidence?
- What does the current Australian guideline say about it?
- What is the total cost of the full course?
- What happens if it does not work — what is the next step?
- Is cartilage regeneration being claimed?
That last one is diagnostic. If the answer is yes, you have learned something important about the advice you are receiving.
Where this leaves you
If you have arrived here because you are looking for an alternative to surgery, that is a completely reasonable place to be, and the answer is not that nothing works.
Exercise and weight management work, are strongly recommended, and cost a fraction of any of this. Cortisone works for short periods. Beyond those, the honest answer is that the cupboard is emptier than the advertising suggests — and that a knee replacement, when it is genuinely warranted, is one of the more reliable operations in medicine.
Back to the overview, or read about tablets and supplements.
Do PRP injections work for knee arthritis?+
The Australian guideline makes no recommendation either for or against platelet-rich plasma for knee osteoarthritis, on the basis that there is not enough high-quality evidence to support one. That is different from a finding that it does not work — it means the question has not been settled. Trials exist on both sides, preparation methods vary enormously between providers, and that variation is part of why the evidence has not converged.
Do stem cell injections work for knee arthritis?+
The Australian guideline does not recommend offering stem cell therapy for knee osteoarthritis, and international guideline reviews have found strong recommendations against it. This is a firmer position than the one taken on PRP. It is also the treatment most often sold with the strongest claims, which is an uncomfortable combination worth being alert to.
Can stem cells or PRP regrow cartilage in my knee?+
No treatment currently available has been shown to regrow cartilage or reverse established arthritis in a knee, including PRP and stem cell injections. If regeneration is being promised to you, that promise is ahead of the evidence. Australian advertising rules for regulated health services prohibit creating unreasonable expectations of benefit, and claims of cartilage regrowth fall into that territory.
How much do PRP and stem cell injections cost in Australia?+
Both are generally out of pocket, and neither is typically covered by Medicare for knee osteoarthritis. PRP commonly runs to several hundred dollars per injection, often recommended as a course. Stem cell treatments are usually considerably more, sometimes into the thousands. Ask for the total cost of the full recommended course rather than a per-injection figure.
Are PRP and stem cell injections safe?+
The direct risks are relatively low — most problems are local pain, swelling or a reaction after injection, with serious complications uncommon. The more realistic harms are financial, and the opportunity cost of months spent on an unproven treatment rather than on the exercise and weight management that have strong evidence behind them.
What should I ask before paying for a PRP or stem cell injection?+
Ask what the treatment is expected to achieve and on what evidence; what the total cost of the full course is; what the current Australian guideline says about it; and what happens if it does not work. Ask specifically whether cartilage regeneration is being claimed, and treat that claim as a warning sign rather than a selling point. A clinician who answers all of these plainly is worth trusting more than one who does not.