PRP, Stem Cell, and “Miracle German Cartilage Growing” Injections Explained
Following on from our last blog on cortisone injections, I want to turn our attention to two treatments you’re likely hearing more and more about (and probably already have): Platelet-Rich Plasma (PRP) – more commonly known as “blood injections” – and Stem Cell injections. Both are often marketed as “cutting-edge regenerative medicine,” and both are increasingly being offered to people with for various ailments, commonly the knee joint (especially stem cells) and tendon problems (especially PRP) here in Australia.
Whilst this is not an intervention that we, as physio’s, can prescribe, we do need to know enough about it to be able to help you make an informed decision regarding the problems you present to us with. It is so common for people to come in and ask us what we think based on “my neighbour said I should have this injection”, or the dreaded “Dr Google told me…”. So my role isn’t to tell you whether or not to proceed with these injections (if in fact either has been suggested) — it’s to give you some honest, evidence-based information to help you make that informed decision for yourself. So, let’s have a good look, based on my knowledge, at what these treatments actually are, and what the science actually says.
What Are We Actually Talking About?
PRP starts with a small sample of your own blood, spun in a centrifuge to concentrate the platelets which are the cells involved in clotting and healing. That concentrated solution is then injected back into your painful joint or tendon, on the theory that more platelets means more healing signal. In theory, it sounds amazing. And the risks – relatively low as it is your own blood after all.
Stem cell therapy usually involves harvesting cells from your bone marrow or body fat, then injecting them into an arthritic joint. These are often called the body’s “master cells” because of their potential to develop into different tissue types — and it’s this potential that fuels the promise of regrowing cartilage.
Both ideas are theoretically and biologically plausible. But the clinical evidence isn’t quite strong enough yet to consider either as “miracle cures”.
What Does the Research Actually Show?
In 2025, an Australian-led team published the largest and most rigorous review to date through the independent Cochrane Collaboration, analysing 25 randomised trials involving more than 1,300 people with knee osteoarthritis.
For stem cell injections, the review found they may offer small improvements in pain and function for some people — but there is no convincing evidence they regenerate cartilage, and no evidence they slow the progression of arthritis. Long-term safety and effectiveness remain uncertain, and the overall quality of evidence was rated low to very low.
For PRP, the picture is even murkier — and it depends heavily on the area being treated. Some studies show benefit, others show none — largely because there is no standardised way of preparing it. Every clinic’s centrifuge, platelet concentration, and injection protocol can differ, meaning researchers are often comparing entirely different products under the one name. For knee osteoarthritis specifically, this inconsistency means current Australian and international guidelines do not recommend PRP as routine care.
It’s worth noting, though, that PRP’s track record for tendon problems — things like tennis elbow, plantar fasciitis (although not a tendon problem), and patellar tendinopathy — is somewhat more encouraging than for arthritic joints, with several trials showing genuine benefit over corticosteroid injections at longer-term follow-up. So the honest answer to “does PRP work?” really is “it depends what you’re using it for” — which is exactly the kind of nuance the marketing tends to skip over.
Personally, I haven’t had enough people with stem cell intervention (probably due to its cost factor) to make comment. And regarding PRP, I’ve had heaps of patients have the injection and the simple fact is I just never know who it will and won’t work for. For some it has been the “miracle cure”, yet for the majority the results have been fair to middling at best.
In plain terms: the science simply hasn’t caught up with the (very convincing) marketing yet.
“But I Know Someone It Worked Brilliantly For…”
I hear this often, and I never dismiss it — people’s experiences are real and valid. But pain improves for all sorts of reasons: natural healing, increased activity, strength gains, and yes, genuine placebo response. This is precisely why we rely on well-designed clinical trials rather than individual stories, however compelling they are. One good outcome doesn’t prove a treatment works — and one disappointing outcome doesn’t prove it doesn’t. That’s the nature of evidence-based care, which is what we always try and bring you at SSPC.
Can They Regrow Cartilage?
This is the claim that probably raises the most concern, because it’s the one most likely to lead someone toward an expensive decision based on false hope. At present, there is no convincing, high-quality evidence that either PRP or stem cell injections regenerate cartilage in people with osteoarthritis. That’s not the same as saying it’s impossible — simply that it hasn’t been demonstrated. If that breakthrough existed, it would reshape arthritis care worldwide — we’re simply not there yet.
A Word on Cost
These treatments generally aren’t covered by Medicare when used for osteoarthritis. PRP typically can cost in the range of $350–$1,200 per injection, while stem cell procedures commonly range from $3,000 to $9,000 or more — and some people undergo multiple rounds.
“But Haven’t German Scientists Invented a Miracle Cartilage Growing Gel?”
How many times have I been shown this in the last 6 months? Viral social media posts claiming that German scientists have engineered a new “miracle gel” capable of fully regrowing knee or hip cartilage without surgery are a classic case of internet exaggeration. The product being advertised is almost certainly “ChondroFiller”, developed by German biomedical firms. The posts look professional, the headline captivating, the information exciting, but in reality, these posts often twist real medical milestones into misleading clickbait.
This product provides a classic example of the difference between the “marketing” and the “reality””
- ChondroFiller is Not New:
The timelines are totally incorrect: Viral posts often state this is a brand-new discovery. In reality, ChondroFiller has been approved and used across Europe since 2013.
- The Misconception of “No Surgery”:
Another misleading claim online is that this gel is a simple, non-surgical outpatient injection, akin to a routine cortisone or PRP injection However an operating theatre is required as ChondroFiller must be precisely implanted during an arthroscopic (keyhole) surgery under general or local anaesthesia.
- Widespread Osteoarthritis vs. Focal Defects:
Social media falsely markets this gel to individuals suffering from advanced, “bone-on-bone” osteoarthritis. However, this gel at best appears to be best used for small isolated focal defects, not the more widespread arthritic change seen in degenerative joints.
- The Reality of Rehabilitation
Viral clips imply patients can walk away pain-free almost instantly. The real clinical recovery protocol demands strict adherence to: Immobilisation: The joint must be entirely immobilized or strictly protected from weight-bearing forces for the first 48 hours to allow the hydrogel matrix to properly set; Tissue Maturation: The gel doesn’t immediately become tough cartilage. It takes anywhere from 6 to 24 months for migrating cells to populate the matrix and density to match original tissue strength; Intensive Physio: Patients must complete months of structured rehabilitation to safely restore joint range of motion and preserve the fragile, maturing repair tissue.
My Honest Advice
I’m definitely not closing the door on PRP or stem cell therapy forever. Research is ongoing, and future high-quality studies may well identify the specific patients who genuinely benefit. But today’s evidence doesn’t yet support the sweeping promises often made in advertising – just be so careful and wary of what you are reading. I get more requests for information from patients regarding information they have seen on social media and google feeds, than from their qualified medical practitioner.
Four Things Worth Remembering
- There’s currently no high-quality evidence that PRP or stem cell injections regrow worn cartilage.
- Stem cell injections may offer small pain benefits for some, but the evidence is uncertain.
- PRP shows more promise for tendon problems than for arthritic joints, but results remain inconsistent — it isn’t currently recommended as routine care for knee osteoarthritis.
- Exercise remains the single most evidence-backed treatment for osteoarthritis, and for tendon problems!
Anthony Lance
SSPC Physiotherapist
References available on request.
