Can knee cartilage be regrown?
It is the right question. Most people asking it are not looking for another painkiller — they want the joint repaired, not managed. Here is where the question of how to regenerate cartilage actually stands: what has been rebuilt in humans, in whom, and what happened when a drug genuinely did regrow cartilage in an arthritic knee.
The short answer
Yes, for some people. Cartilage is being regrown in patients today, with approved products, in hospitals.
But almost none of those people have osteoarthritis. That is the distinction the entire subject turns on, and it is the reason the search results are so confusing.
Where cartilage regeneration genuinely works
If you have a focal cartilage defect — a discrete hole in the cartilage, usually from an injury, in an otherwise healthy joint — there are real procedures that grow new cartilage to fill it.
Cells are taken from your own knee, grown in a laboratory over several weeks, and implanted back into the defect. Spherox, developed by the German company CO.DON, condenses those cells into spheroids; it holds European marketing authorisation for cartilage defects and has been introduced at NHS hospitals in the UK.1 MACI is the equivalent used in North America.
The evidence is reasonable. In the SUMMIT trial, MACI outperformed microfracture on pain, function and daily activities.2 A smaller series of 22 patients followed five to seven years afterwards found sustained improvement, with 19 of them saying they would have the procedure again.3
A systematic review of the randomised trials of cartilage repair with at least five years of follow-up judged all of them to be at high risk of bias, because patients and assessors could not be blinded to which operation they had.2 That does not make the results wrong. It means they are less certain than the numbers alone suggest.
Who qualifies
This is where most people asking the question fall out.
| Criterion | Typical requirement |
|---|---|
| Age | Roughly 18 to 55; trial populations average in the mid-thirties2 |
| The problem | A discrete defect, commonly traumatic — not diffuse wear |
| Size | Around 2 to 10 cm², in a defined location1,3 |
| The rest of the joint | Otherwise healthy, correctly aligned, meniscus intact3 |
| What it involves | Two surgeries, weeks apart, with laboratory cell culture between |
Osteoarthritis is the opposite picture: cartilage thinning across the joint surface rather than a hole in it, with changes in the bone underneath and the joint lining as well. There is no edge to fill in. That is why these procedures are not offered for it.
If you are under 55, your knee problem began with a specific injury, and you have been told you have a cartilage defect rather than arthritis, this is a real avenue and you should ask an orthopaedic surgeon about it. We do not offer it. We would rather you knew it existed.
What happened when a drug actually did regrow cartilage
This is the part almost nobody is told, and it is the most important thing on this page.
Sprifermin is a recombinant human fibroblast growth factor. The FORWARD trial injected it into the knees of 549 people with osteoarthritis and followed them for five years — the longest trial of its kind reported.4
It worked, structurally. Cartilage thickness increased, dose-dependently, measured on MRI, and the gain was still present three and a half years after the last injection.4 In a later analysis, treated knees showed roughly double the cartilage thickening seen without the drug, while cartilage thinning fell close to the rate observed in a healthy reference group drawn from the Osteoarthritis Initiative.5
That is cartilage regeneration in humans with osteoarthritis. Demonstrated, published, repeated.
Everyone improved — the sprifermin groups and the placebo group alike. The extra cartilage did not translate into people feeling better.4,6
It is worth understanding why, because it is not a trick of statistics. The measured difference in cartilage thickness was about 0.05 mm.4 Real, consistent, statistically robust — and a fraction of a millimetre. Growing cartilage and restoring a knee are not the same achievement.
An analysis of a subgroup with more advanced disease at the start found a pain difference favouring the drug by year three, still present at year five. The size of that difference cleared the threshold for a meaningful change, but the range of uncertainty around it included no difference at all — so it is a lead, not a finding. It was also identified after the trial rather than planned in advance.4
No disease-modifying osteoarthritis drug has been approved in Europe or the United States.5 Sprifermin is not available to you.
The German treatment you have read about
If someone has mentioned a treatment from Germany, it is most likely Orthokine — sold as Regenokine in the United States. It was developed in Düsseldorf and became widely known when Kobe Bryant, Alex Rodriguez and Fred Couples travelled there and credited it publicly.7
Your own blood is incubated so that it produces high levels of interleukin-1 receptor antagonist — a molecule that blocks one of the drivers of joint inflammation — and the serum is injected back into the knee.8
The symptom evidence is better than most people assume. The GOAT trial randomised 376 patients with knee osteoarthritis, blinded both patients and observers, and used a placebo control. It found in favour of the treatment.9 That is a larger and better-designed trial than much of what surrounds it.
The authors are explicit that they enrolled only patients with severe pain scores at the outset, and that the results cannot necessarily be generalised to all osteoarthritis patients. The conclusion was drawn for low- to medium-grade disease.9 If you have been told your arthritis is advanced, that trial was not studying you.
What it has not shown is regeneration. Animal work suggested a protective effect on cartilage; human trials have not confirmed structural preservation. And patients followed for eleven years afterwards had reduced symptoms but no significant delay in eventually needing a joint replacement in advanced arthritis.7
Can you get any of this in Canada?
Not readily, and not for arthritis.
The cartilage repair procedures are for focal defects, are surgical, and are done in a small number of specialist centres. Spherox holds European authorisation and is not the standard route here. If you have a defect rather than arthritis, the conversation to have is with an orthopaedic surgeon, not a private clinic.
Sprifermin is not approved anywhere and exists only inside research.5 Orthokine is a German treatment offered in Germany; cell-based therapies of this kind are regulated as drugs in Canada and require authorisation before they can be offered, which is a subject we cover on our page about stem cell injections.
So if you are searching for somewhere in Canada that will regenerate the cartilage in an arthritic knee, the honest answer is that no such place exists — here or anywhere else.
So where does that leave the question
Plainly: nothing available today has been shown to regenerate cartilage in a knee that is diffusely arthritic. Not stem cells. Not Orthokine. Not platelet-rich plasma. Not what we do.
Treatments that grow cartilage work on defects, not on arthritis. The one drug that measurably grew cartilage in arthritic knees grew a twentieth of a millimetre and did not change how people felt. This is not a case of the answer being hidden behind a border or a paywall. It is a case of the answer not existing yet.
Any clinic telling you otherwise is describing something the published evidence does not support.
What is left, and it is not nothing
Osteoarthritis was never only a disease of cartilage. It involves the whole joint — the cartilage, the bone beneath it, and the synovium, the lining that wraps the joint and produces its fluid. The lining is not a bystander in that process; it is part of the disease.10
That matters for what is realistically achievable. Nothing available restores what has been lost. But a treatment acting on the joint lining is acting on part of the disease process rather than on the sensation alone — and it can do so in a joint where the cartilage is long gone, because it is not depending on cartilage to work.
That is a more modest claim than regeneration and we are not going to dress it up as more. What we do is a single injection of a permanent hydrogel implant that is drawn into the joint lining and stays there. It does not degrade, it is not repeated, and it is not a painkiller. It also does not rebuild your knee, and we will not tell you it does. The studies behind it, and their limits, are on our research page.
The honest way to think about it
For most people over sixty, the real choice is not between rebuilding the joint and patching it up. Rebuilding is not on the menu — for anyone, anywhere, yet. The choice is between living with the knee as it is, replacing it, or changing the environment inside it.
Understanding that is not a consolation prize. It is the difference between making a decision and continuing to look for something that has not been invented.
Sources
- European Medicines Agency marketing authorisation for Spherox (CO.DON), for symptomatic articular cartilage defects of ICRS grade 3 to 4 up to 10 cm² in the knee in adults; NHS Royal Orthopaedic Hospital account of its use. Read the hospital account
- SUMMIT trial (NCT00719576), Saris et al 2014. Randomised open-label study of MACI versus microfracture, 144 patients, ages 18 to 55, mean age 33.8, symptomatic grade III or IV focal defects of at least 3 cm². Summarised in payer coverage criteria. Read the summary
- Treatment of cartilage defects in the patellofemoral joint with matrix-associated autologous chondrocyte implantation: 5 to 7 year outcomes. Read the paper
- Long-term structural and symptomatic effects of intra-articular sprifermin in patients with knee osteoarthritis: 5-year results from the FORWARD study. Annals of the Rheumatic Diseases. Trial registration NCT01919164, 549 participants. Read the paper
- Intra-articular sprifermin reduces cartilage loss in addition to increasing cartilage gain: post-hoc analysis of the FORWARD study, including comparison with a healthy reference cohort, and noting that no disease-modifying osteoarthritis drugs are approved in Europe or the USA. Read the analysis
- Sprifermin for treatment of osteoarthritis: review of the completed randomised controlled trials, reporting sustained increase in cartilage thickness and volume without corresponding improvement in symptoms or joint function versus placebo across whole study populations.
- Review of Orthokine and Regenokine autologous conditioned serum, including the origin of the treatment in Düsseldorf and the eleven-year follow-up finding reduced symptoms without significant delay in eventual joint replacement in advanced osteoarthritis. Read the review
- Treatment of knee osteoarthritis with Orthokine-derived autologous conditioned serum. Expert Review of Clinical Immunology 2010. Read the abstract
- Autologous conditioned serum is an effective treatment for knee osteoarthritis. Osteoarthritis and Cartilage. The German Orthokine Osteoarthritis Trial: 376 patients, prospective, randomised, patient- and observer-blinded, placebo-controlled. Read the trial
- Hunter DJ, Bierma-Zeinstra S. Osteoarthritis. Lancet 2019;393(10182):1745–59.
This page is general information about treatments for knee osteoarthritis and cartilage injury. It is not a diagnosis and it is not medical advice about your knee. It describes what the published research reports; it is not a comment on any individual clinic or practitioner. Whether any treatment is appropriate for you depends on what is happening inside your joint, which is what an assessment is for.