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Arthrosamid® knee injection
A single-visit hydrogel injection for mild-to-moderate knee osteoarthritis. Delivered under live ultrasound by a trained consultant, with structured follow-up so you know how you're getting on.
Arthrosamid® is a 2.5% polyacrylamide hydrogel injected into the knee joint to help manage the symptoms of mild-to-moderate osteoarthritis. It is not a steroid, and not made from your own blood, it is a biocompatible gel that stays in the joint and is not absorbed by the body. At Prime Health it is delivered by trained consultants under live ultrasound guidance, following a consultant assessment to confirm it is the right option for your knee. We offer Arthrosamid® at our centres in London, Surrey, Sussex and Greater Manchester.
What Arthrosamid® is
Arthrosamid® is a hydrogel, 97.5% water, 2.5% cross-linked polyacrylamide, designed to sit in the joint and integrate with the tissue lining it, the synovium. It is intra-articular (injected into the joint space itself), non-biodegradable, and not derived from human or animal material. It received UK approval in 2023 following earlier European approval, and is CE-marked. It is manufactured in Denmark by Contura.
What makes it different from other injections is that it stays in the joint. A steroid injection reduces inflammation for a limited period. A hyaluronic acid injection lubricates the joint and is typically repeated. Platelet-rich plasma (PRP) uses your own blood cells to try to stimulate healing. Arthrosamid® is a mechanical intervention, a gel cushion, that is designed to give a longer duration of effect from a single treatment.
How Arthrosamid® works
The gel is injected directly into the joint space under live ultrasound guidance, so the consultant can see exactly where the needle is throughout the procedure. Over the following weeks, the hydrogel gradually integrates with the synovium, the tissue that lines the knee joint capsule. Once settled, it stays in place. Because it is not biodegradable, the body does not clear it in the way it clears a steroid or a viscosupplement.
Because it is delivered under ultrasound rather than blindly, the injection is accurate and the medication reaches the correct joint compartment. Blind injections into the knee miss the joint space in a meaningful proportion of cases; ultrasound guidance essentially eliminates that.
Who Arthrosamid® can help
Arthrosamid® is used for adults with radiologically confirmed mild-to-moderate knee osteoarthritis whose symptoms are affecting day-to-day life, and where simpler measures, activity modification, weight management, pain relief, physiotherapy or earlier injections, have not given enough relief.
Because it is a single-visit procedure, it can be particularly useful for people whose knee pain limits work, sport, sleep, caring responsibilities or planned events, and who want a treatment plan that does not depend on repeated appointments over the following weeks. It is also often considered by people looking to defer or avoid knee replacement surgery, in circumstances where their osteoarthritis is not yet advanced enough to require it.
Who it is not for
Arthrosamid® is not suitable for everyone. Your consultant will discuss alternatives with you if any of the following apply:
- Advanced (severe, bone-on-bone) osteoarthritis of the knee, where a joint replacement is the more appropriate option.
- Active infection in or around the joint, or an untreated skin condition over the injection site.
- An inflammatory arthritis (for example, rheumatoid arthritis or gout) that has not been assessed and managed.
- Pregnancy, or planning to become pregnant.
- Certain anticoagulant regimens or bleeding disorders, until reviewed.
- Any of the specific contraindications identified at your consultation.
Where Arthrosamid® is not the right treatment for you, your consultant will explain what is, and we can arrange the next step at the same centre where possible, including onward referral for joint replacement where that is the right answer.
How Arthrosamid® compares to other treatments
Reduces inflammation for a limited period (typically weeks to months). Can be repeated a few times a year. Repeated steroid injections have their own trade-offs and are not a long-term strategy for progressive osteoarthritis.
Also called viscosupplementation. Lubricates the joint and is typically repeated periodically. Effect is temporary because it is absorbed.
Prepared from your own blood; injected in one or several sessions. Aims to stimulate the joint's own repair processes. See our page on PRP and nStride for more.
Non-biodegradable hydrogel, delivered as a single injection in most patients. Stays in the joint, acting as a mechanical cushion. Structured follow-up at 3, 6 and 9 months.
The right answer for advanced (bone-on-bone) osteoarthritis. Definitive but a larger undertaking with a longer recovery. Arthrosamid® is one of several options that can defer surgery for appropriately selected patients.
The foundation for every knee, whichever injection or procedure is added. On our Premium package, physiotherapy is part of the Arthrosamid® pathway.
What happens on the day
Your appointment usually takes 30 to 45 minutes. Your consultant confirms the plan with you, cleans the skin, and uses a small amount of local anaesthetic to make you comfortable. Live ultrasound is used to guide the needle accurately into the joint space so the injection lands exactly where it should. Most people describe the injection itself as a brief pressure sensation rather than sharp pain.
Afterwards, we ask you to rest quietly for a short period before you go home. You should not drive immediately after the procedure, please arrange to be collected, or plan to travel by taxi or public transport.
Recovery, what to expect, week by week
Recovery from Arthrosamid® is straightforward for most patients. The knee is often sore for a few days, then eases; benefit builds over several weeks.
Rest, ice, elevate. Some soreness and mild swelling is common. Simple painkillers (paracetamol, ibuprofen if suitable) are usually all that is needed.
Gentle daily activity is fine, desk work, short walks, driving after a couple of days. Avoid strenuous exercise, heavy lifting, running or long standing to give the hydrogel a chance to settle.
Return to normal activities. If you are on our Premium package, your first physiotherapy session is around week two, followed by two more in the weeks that follow.
Fuller benefit typically develops as the hydrogel settles into the joint. Sport, running and gym work are usually reintroduced from around six weeks, guided by symptoms.
WOMAC outcome tracking, a brief validated questionnaire on pain, stiffness and function, completed by text or on paper. Your consultant reviews the results with you.
Because the hydrogel is not biodegradable, it stays in the joint. Contura's published data shows benefit maintained out to five years post-injection. Individual results vary; we will be honest with you about how you are doing.
Follow-up and outcome tracking
Every Arthrosamid® patient at Prime Health is offered follow-up outcome tracking using the WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) questionnaire, a validated, widely-used measure of knee pain, stiffness and function, at 3, 6 and 9 months after the procedure. You can complete this by text message via Data Biologics, the same outcome-tracking platform many UK regenerative-medicine services use, or on paper if you prefer.
Two things matter here. Your consultant sees the same results you do, so we can pick up early if you are not doing as well as hoped and act on it. And you have your own record of the change, in a form that means something clinically. Not every private provider does this.
Two ways to have Arthrosamid® at Prime Health
Consultant assessment, ultrasound-guided Arthrosamid® injection in a single visit, aftercare guidance, and structured WOMAC outcome tracking at 3, 6 and 9 months.
Everything in the Standard package, plus a physiotherapy review on the day of your injection to set expectations and rehab plan, and three physiotherapy sessions in the weeks after, the first about two weeks post-procedure, to help you get the best from the treatment.
Prices for each package vary by centre. Call us on 0330 025 2100 for the current fees, or enquire below and our team will confirm.
Why Prime Health for Arthrosamid®
- Trained consultants. Arthrosamid® at Prime Health is only delivered by consultants trained in the procedure by the manufacturer. We check certification before we let anyone loose on a patient.
- Ultrasound-guided every time. Live ultrasound is used to guide the needle. No blind injections.
- Diagnostics on site. If you need an MRI or an X-ray before the injection, or a scan to confirm progression, it happens in the same building rather than in a separate appointment at a separate provider.
- WOMAC outcome tracking as standard. Not an add-on. Structured follow-up at 3, 6 and 9 months, so we know what actually happened.
- Optional Premium physiotherapy package. Pre-procedure physio review plus three post-procedure sessions to give you the best chance of a good outcome.
- Multi-centre. Available across our London, Surrey, Sussex and Greater Manchester centres, so you can be seen close to home.
- Regulated care. Every Prime Health centre is registered with the Care Quality Commission. Our reporting is held to the same standard as our NHS-facing work.
Clinical evidence
Arthrosamid® has been studied in several published trials sponsored and reported by the manufacturer, Contura. Follow-up data out to five years post-procedure has been published in peer-reviewed journals, and outcome tracking using the WOMAC questionnaire is a standard part of the evidence base.
The evidence describes Arthrosamid® as most useful for mild-to-moderate osteoarthritis. In line with the published data, we are honest that Arthrosamid® is not a cure for osteoarthritis and does not replace the underlying joint changes; it is a treatment to manage symptoms and function. For advanced (bone-on-bone) disease, joint replacement remains the mainstay of care.
If you would like to read the underlying studies before your consultation, ask our team and we will send you the references.
What to think about beforehand
- Is your osteoarthritis mild-to-moderate rather than advanced? An up-to-date MRI or weight-bearing X-ray answers this.
- Have simpler measures (activity change, physio, pain relief) had a fair go?
- Are you clear about what Arthrosamid® is and is not, and what alternatives you have?
- Have you had a chance to ask about the risks, and about what happens if it does not work as well as you hoped?
- If you are on any anticoagulant, have you told us at booking so we can plan safely?
Frequently asked questions
The questions patients most often ask us about Arthrosamid®, from what it is to how long it lasts.
What is Arthrosamid® made of?
Arthrosamid® is a 2.5% polyacrylamide hydrogel, 97.5% water and 2.5% cross-linked polyacrylamide. It is not derived from human or animal material, is CE-marked, and is manufactured in Denmark by Contura.
Who is Arthrosamid® suitable for?
Adults with radiologically confirmed mild-to-moderate osteoarthritis of the knee whose symptoms are affecting day-to-day life, and where simpler measures, activity modification, weight management, pain relief, physiotherapy, or earlier injections, have not given enough relief. Suitability is confirmed by consultant assessment before treatment.
Who is Arthrosamid® not suitable for?
It is not the right treatment for advanced (bone-on-bone) osteoarthritis, active infection in or around the joint, untreated inflammatory arthritis such as rheumatoid arthritis or gout, pregnancy, certain blood-thinning regimens, or where an alternative is more appropriate. Your consultant will explain what is best for your knee.
How does Arthrosamid® work?
Arthrosamid® is injected into the joint space and gradually integrates with the tissue lining the joint, the synovium. It stays in the joint, does not biodegrade, and acts as a cushion within the joint. This is different from a steroid (which reduces inflammation for a limited time) and different from hyaluronic acid (which lubricates the joint and is typically repeated).
How long does an Arthrosamid® injection take?
The appointment usually takes 30 to 45 minutes. The injection itself is short. Most of the appointment is consent, ultrasound assessment, the injection, and post-procedure instructions.
Is Arthrosamid® painful?
The injection is done under ultrasound guidance using a small needle, and local anaesthetic is used to keep you comfortable. Most people describe it as a brief pressure sensation rather than sharp pain. Some soreness and mild swelling in the joint for a day or two afterwards is common.
When will I feel the benefit?
Some people notice improvement within the first two to four weeks, but the fuller benefit typically develops over 8 to 12 weeks as the hydrogel settles into the joint. Your consultant, and, on our Premium package, your physiotherapist, will guide you through what to expect week-by-week.
How long does Arthrosamid® last?
Contura's published clinical data includes follow-up out to five years. Individual results vary and depend on how advanced the osteoarthritis is when treated; some patients maintain improvement longer than others. Because we track WOMAC scores at 3, 6 and 9 months, you and your consultant have an honest read on how you are actually doing.
Can I have both knees done?
Yes, bilateral treatment is possible, but each knee is assessed on its own merits. Whether both are done on the same day or on separate visits is a clinical decision your consultant will discuss with you.
Can Arthrosamid® be repeated?
Because Arthrosamid® is a non-biodegradable hydrogel that remains in the joint, most patients are not routinely re-injected. In selected cases a further dose is considered, this is a clinical decision.
Do I need a referral?
Yes. Arthrosamid® is not a self-refer treatment. Every patient has a consultant assessment before we proceed. If you already have a consultant, ask them to refer you; if not, our team will arrange the consultation for you.
What are the risks and side effects?
Common short-term effects include soreness, mild swelling and a feeling of heaviness in the knee for a few days after the injection. Rare complications include infection, allergic reaction and a temporary increase in stiffness. Your consultant will discuss the full risk profile with you before you consent.
How does it compare to a steroid injection?
A steroid injection acts by reducing inflammation and typically gives relief for a limited period (weeks to months). It can be repeated a few times a year but repeated steroid exposure has its own trade-offs. Arthrosamid® is a mechanical rather than anti-inflammatory intervention, it works differently and is designed to provide a longer duration of effect from a single treatment.
How does it compare to hyaluronic acid?
Hyaluronic acid (also called viscosupplementation) lubricates the joint and is usually repeated periodically. Arthrosamid® is not absorbed by the body and stays in the joint, which is why it is offered as a single-visit treatment in most cases.
Can Arthrosamid® delay a knee replacement?
For appropriately selected patients, Arthrosamid® can be a way to manage symptoms and defer joint replacement surgery. It is not a substitute for surgery in advanced osteoarthritis. Your consultant will be honest with you about where you are on that spectrum.
Will you follow up on how I am getting on?
Yes. Every Arthrosamid patient at Prime Health is offered WOMAC outcome tracking at 3, 6 and 9 months post-procedure. You can complete this by text message or on paper. Your consultant sees the same results, so we can pick up early and act on it if you are not doing as well as hoped.
Clinicians providing Arthrosamid® at Prime Health
Every clinician listed below is Contura-certified to deliver Arthrosamid®. Contact their secretary directly to arrange a consultation and mention that you would like to be seen at our centre.
More consultants join the Arthrosamid® service as Contura training completes. Not sure who to see? Call 0330 025 2100 and our team will point you the right way.
Related at Prime Health
Where a scan, a specialist opinion or another treatment might be part of the picture.
Joint, bone and muscle
The end-to-end pathway from a joint problem to a scan, a specialist plan and treatment where it helps.
Knee MRI
If your consultant needs up-to-date imaging before treatment, we scan and report on site.
Ultrasound-guided injections
The image-guided technique used to deliver Arthrosamid® and other joint injections accurately.
Orthopaedic consultants
The orthopaedic surgeons and specialists at Prime Health across our four centres.
Enquire about Arthrosamid®
Tell us a little about your knee and our team will arrange a consultant assessment and answer your questions. All private and confidential.