On this page
- What hip osteoarthritis does
- Standard treatment comes first here too
- Why the hip is studied so much less
- What evidence actually exists
- Whether knee results should transfer
- Who might be considered
- Risks and the delivery question
- Questions to ask about this joint specifically
- Frequently asked questions
- Requesting a medical evaluation
Almost everything written about stem cells and hips is borrowed from knees. Hip osteoarthritis and stem cell therapy has a far thinner evidence base than the knee does, for reasons that are practical rather than biological — and a clinic quoting knee trials while proposing to inject your hip should say that is what it is doing.
What hip osteoarthritis does
The same disease process as in the knee — cartilage thinning, bone remodelling, episodic synovial inflammation — in a joint built quite differently.
The hip is a deep ball-and-socket joint carrying load through a small congruent surface. Pain is classically felt in the groin, and referred pain to the thigh or knee is common enough that people arrive convinced the problem is somewhere else.
Stiffness shows up early in rotation. Putting on socks and getting out of a car are the everyday movements that go first, and they are useful markers of progression.
Unlike the knee, the hip has little capacity to compensate through muscle control, which is part of why it tends to progress more predictably once it starts.
Standard treatment comes first here too
Exercise therapy, particularly hip abductor strengthening, has genuine evidence and is consistently underused.
Weight management, simple analgesia and activity modification cover most of the middle ground. Image-guided corticosteroid injection provides short-term relief and is sometimes used diagnostically to confirm the joint is the pain source.
Hip replacement is one of the most consistently successful operations in medicine, with high satisfaction and long implant survival. That sets a high bar for any alternative in advanced disease.
See osteoarthritis for the general picture.
Why the hip is studied so much less
Access. The knee is superficial and can be injected accurately in a consulting room; the hip is deep and needs ultrasound or fluoroscopic guidance to inject reliably.
That single fact raises trial cost, requires imaging expertise at every visit, and introduces variability in whether the injection reached the joint at all.
There is also less of a patient pool at the mild-to-moderate stage, because hip disease is often diagnosed later — people attribute early groin pain to muscles or backs.
None of those reasons are about the biology being different, which is exactly why extrapolation is tempting.
What evidence actually exists
The pooled analyses in this field are knee analyses. The 2025 systematic review and meta-analysis is specific to the knee — Efficacy and safety of mesenchymal stem cells in knee osteoarthritis — as is the 2024 network meta-analysis comparing cell types — which cell and type are more beneficial.
Broader reviews of biologic injection in osteoarthritis and cartilage damage cover the territory more generally — Biologic injections for osteoarthritis and articular cartilage damage: can we modify disease? — and mechanistic reviews of cartilage regeneration are not joint-specific — Stem cells in articular cartilage regeneration.
What does not exist is a body of randomised hip trials comparable to the knee literature. Anyone implying otherwise is describing a literature that has not been written.
Whether knee results should transfer
There is a reasonable argument that they might. The tissue is the same, the disease process is the same, and a mechanism acting on joint inflammation has no obvious reason to care which joint it is in.
There are reasonable arguments against. Load per unit area differs. Joint volume differs, so the same cell count produces a different concentration. Depth affects delivery accuracy. And hip pain has more competing sources — labrum, bursa, spine — so response is harder to attribute.
The honest position is that transfer is plausible and untested. That is a legitimate thing to tell a patient, and quite different from presenting knee data as though it were hip data.
Who might be considered
By analogy with the knee trials: mild to moderate disease, cartilage remaining, conservative treatment already tried, and realistic expectations.
Advanced disease with significant bone change is where replacement has a strong evidence base and injection has none.
Hip dysplasia, impingement and avascular necrosis are different problems with different management, and need identifying before anything is injected.
Accurate diagnosis matters more here than at the knee, because more things refer pain to the same place. A diagnostic injection of local anaesthetic into the joint is a cheap way of establishing whether the hip is genuinely the source before anything expensive is contemplated.
Risks and the delivery question
The general risks apply — a small infection risk, transient pain and swelling, and donor-site risks where cells are autologous. See adverse events.
One risk is specific to this joint: an injection that misses. Without imaging guidance, hip injection accuracy is poor, and a preparation delivered into surrounding soft tissue is not the treatment that was studied.
Ask directly whether the injection will be image-guided and by what method. An answer of “we do it by feel” for a hip is a meaningful answer.
Cost is the other consideration people underweight here. Paying knee-trial prices for a procedure with no hip-specific evidence is a different value proposition from paying them for the indication that was actually studied — see the cost page.
Questions to ask about this joint specifically
These differ from the knee questions in ways that matter.
- What randomised evidence exists for hips, as opposed to knees?
- Will the injection be ultrasound or fluoroscopically guided?
- Has my groin pain been confirmed as coming from the joint?
- Have dysplasia, impingement and avascular necrosis been excluded?
- What dose, and how was it adjusted for a joint of different volume?
See the knee page for the literature being extrapolated from.
Ankle osteoarthritis is the third joint in this cluster and is studied even less than the hip.
Frequently asked questions
Is there hip-specific evidence?
Very little. The randomised trials and meta-analyses in this field are knee studies, and hip claims mostly rest on extrapolation from them.
Why has the hip been studied less?
Access, mainly. The knee can be injected accurately in a consulting room; the hip needs imaging guidance, which raises trial cost and complexity.
Does knee evidence apply to hips?
Plausibly, and untested. Load, joint volume, delivery accuracy and competing pain sources all differ. Plausible is not the same as demonstrated.
Should the injection be image-guided?
For a hip, yes. Unguided hip injection accuracy is poor, and a preparation delivered into surrounding tissue is not the treatment studied.
Is it better than a hip replacement?
No trial has compared them. Hip replacement has decades of outcome data and high satisfaction, which sets a high bar in advanced disease.
My groin hurts — is it definitely the joint?
Not necessarily. Labrum, bursa and spine all refer pain there, and confirming the source matters more at the hip than at the knee.
Requesting a medical evaluation
Nothing on this page establishes whether any treatment is appropriate for you. That needs your history, your imaging and your current medications read by a clinician. If you would like that review, send your records and we will tell you honestly whether there is anything worth discussing — including when the answer is no.
This page is general information, not medical advice, and does not create a doctor–patient relationship. Regenerative treatments discussed here are in most cases investigational. Discuss any treatment with a clinician who knows your history.