Arthrosamid vs PRP For Knee Arthritis London. How To Choose
Arthrosamid and PRP are 2 of the most asked-about injections for knee osteoarthritis, and they work in different ways. Arthrosamid is a permanent gel given as a single injection. PRP uses growth factors from your own blood, usually as a short course. Neither regrows cartilage, and the right choice depends on severity, swelling, age and how you feel about a permanent implant.
Key points
In a 2024 randomised trial of 239 patients, a single Arthrosamid injection was as effective as hyaluronic acid for knee pain at 26 weeks, with about 65 percent of patients in each group responding. Side effects at the injection site were more common with Arthrosamid, at 28.9 percent versus 7.6 percent, all mild to moderate.
For PRP, a 2025 meta-analysis of 26 randomised trials favoured it over hyaluronic acid for pain and function, while a 2021 trial in JAMA found no benefit over placebo. The evidence is favourable but contested.
In London, Arthrosamid is typically priced at around £3,000 for 1 knee and £5,000 to £5,900 for both, often with consultation and imaging charged separately. Joint PRP at The London PRP Clinic by The Wellness is from £595 to £995 per treatment.
Arthrosamid is permanent and cannot easily be removed. PRP is your own blood and leaves nothing behind.
Weighing up knee injections? Message our doctors on WhatsApp or email team@thewellnesslondon.com.
What are Arthrosamid and PRP?
Arthrosamid
Arthrosamid is a gel made of 2.5 percent polyacrylamide and 97.5 percent water. It is injected into the knee once, where it integrates into the lining of the joint, the synovium, and is thought to cushion the joint and reduce inflammation in that lining. It is a medical device rather than a medicine, it is designed to be permanent, and it is not absorbed by the body.
PRP
Platelet-rich plasma is prepared from a small sample of your own blood, concentrated to contain several times the normal number of platelets, and injected into the joint. Platelets release growth factors and other signalling proteins that are thought to reduce inflammation and influence the joint environment. Nothing foreign is left in the knee. Most plans involve 1 to 3 injections.
What neither can do
Neither treatment regrows lost cartilage or reverses the changes on an X-ray. Both aim to reduce pain and improve function, and both work best alongside strengthening exercise and weight management.
What does the evidence show?
Arthrosamid
The key randomised trial was published in 2024 in Clinical and Experimental Rheumatology by Bliddal and colleagues, including Professor Philip Conaghan of Leeds. 239 adults with knee osteoarthritis received a single injection of either Arthrosamid or hyaluronic acid. At 26 weeks, knee pain fell by 18.5 points on a 100-point scale with Arthrosamid and by 14.8 points with hyaluronic acid. That met the trial's test for being no worse than hyaluronic acid, but it did not show Arthrosamid was better. About 66 percent of patients with Arthrosamid and 65 percent with hyaluronic acid were classed as responders at 26 weeks, and around 56 percent in each group at 52 weeks.
Device-related side effects, mainly pain, swelling and a feeling of fullness in the knee, affected 28.9 percent of patients after Arthrosamid and 7.6 percent after hyaluronic acid. All were mild to moderate, and there were no serious device-related events. Longer open-label studies report that benefit can last for several years, but these did not have a comparison group.
PRP
PRP for knee osteoarthritis has been studied in many more trials. A 2025 meta-analysis by Bagheri and colleagues in the Journal of Experimental Orthopaedics pooled 26 randomised trials with 6 and 12 month follow-up and favoured PRP over hyaluronic acid for pain and function. On the other side, a well-conducted 2021 randomised trial in JAMA by Bennell and colleagues found PRP no better than a saline placebo at 12 months. We describe the evidence for PRP in knee arthritis as favourable but contested, and we explain both sides before anyone decides. Our full review is in PRP vs hyaluronic acid.
Comparing them directly
There are no large randomised trials comparing Arthrosamid with PRP head to head. Both have been compared with hyaluronic acid, and both performed at least as well as it. Any clinic claiming one is proven superior to the other is going beyond the evidence. For a wider comparison that also covers steroid, see which knee injection is right for arthritis.
Want a clear view of which suits your knee? Ask our doctors on WhatsApp.
Which is better for my knee, Arthrosamid or PRP?
PRP may suit you better if
You have mild to moderate osteoarthritis. You would prefer a treatment made from your own blood that leaves nothing permanent in the joint. You want the option of repeating treatment or changing approach later. You have a tendon, ligament or meniscus problem alongside arthritis, which PRP can also address. Our meniscus guide is PRP for meniscus tear.
Arthrosamid may suit you better if
You have moderate to more advanced osteoarthritis with a knee that swells. You want a single injection and accept that it is permanent. You have had limited benefit from previous injections and want to delay a knee replacement.
Neither may be right if
Your knee locks or gives way, which suggests a mechanical problem. You have severe end-stage arthritis with pain at rest and at night, where a surgical opinion is the right next step. You have inflammatory arthritis that is not controlled, or an infection anywhere in the body. Our guide for younger patients facing this decision is told you are too young for a knee replacement.
What about steroid and keyhole surgery?
Steroid injections relieve pain quickly but usually for weeks rather than months, and repeated injections are best avoided. Keyhole surgery to wash out or trim an arthritic knee is not recommended, as we explain in keyhole knee surgery for arthritis and PRP vs steroid injection.
What happens at The London PRP Clinic by The Wellness?
Assessment
You are assessed by a doctor who examines the knee, hip and the way you walk. X-ray or MRI is arranged at the London centre best equipped for that question if you do not already have recent imaging. You then receive a clear recommendation across every option, including PRP, hyaluronic acid, steroid, Arthrosamid, rehabilitation or a surgical opinion.
If PRP is right
Blood is drawn from your arm and prepared to a consistent, validated protocol, then injected into the knee under image guidance. The appointment takes 45 to 60 minutes and you walk out afterwards. Improvement usually builds over 6 to 12 weeks alongside a strengthening programme, and we review progress at set points.
If Arthrosamid is right
We explain why, and refer you to a specialist colleague who provides it, with your assessment and imaging sent ahead so you do not repeat them.
How much do Arthrosamid and PRP cost in London?
Arthrosamid sits at the top of the market. One central London private hospital lists £3,025 for 1 knee and £5,895 for both, with consultation, diagnostic and specialist fees charged separately, and other UK providers quote from around £2,995 for 1 knee.
At The London PRP Clinic by The Wellness, there are 3 ways to begin.
The diagnostic package, from £695, covers assessment, imaging and blood tests, and gives you a clear recommendation across every option whatever you decide.
Joint PRP is from £595 to £995 per treatment.
A course of 1 to 3 treatments with rehabilitation is what most knee plans involve, with the exact figure confirmed in writing before you commit. More detail is in joint PRP cost in London.
Ask what your knee plan would cost. Message us on WhatsApp.
Why people choose The London PRP Clinic by The Wellness
Every treatment is performed by a GMC-registered doctor, and no clinician treats a patient here until they have completed 100 supervised treatments. Every option is considered at assessment, including ones we do not provide, so the recommendation you receive is the one that fits your knee. We also train other doctors in joint PRP through our Academy.
We see patients across our London clinics, including 10 Portman Square in Marylebone and The Wellness at The Light Centre in Belgravia. Across our work we report an 87 percent patient success rate and more than 187 five-star reviews. How we practise is set out in our clinical standards, and every treatment we offer is in PRP treatment London.
Book your knee assessment. Message us on WhatsApp, email team@thewellnesslondon.com, or call +44 20 3951 3429.
Frequently asked questions about Arthrosamid and PRP
Is Arthrosamid better than PRP for knee arthritis?
There are no large trials comparing them directly. Both have performed at least as well as hyaluronic acid in randomised trials. The choice depends on the severity of arthritis, whether the knee swells and whether you want a permanent implant.
How effective is Arthrosamid?
In a 2024 randomised trial of 239 patients, a single Arthrosamid injection was as effective as hyaluronic acid for knee pain at 26 weeks, with about 65 percent of patients in each group responding.
What are the side effects of Arthrosamid?
Pain, swelling and a feeling of fullness in the knee are the most common. In the 2024 trial, 28.9 percent of patients had a device-related side effect after Arthrosamid compared with 7.6 percent after hyaluronic acid, all mild to moderate.
Is Arthrosamid permanent?
Yes. The gel is designed to stay in the knee permanently and is not absorbed by the body.
How much does Arthrosamid cost in London?
Around £3,000 for 1 knee and £5,000 to £5,900 for both, often with consultation and imaging charged separately. Joint PRP at The London PRP Clinic by The Wellness is from £595 to £995 per treatment.
Can I have PRP after Arthrosamid?
This is a question for the doctor who will treat you, because clinics usually ask for a gap between different injections into the same knee. We advise on timing at assessment.
References
Bliddal H, Beier J, Hartkopp A, Conaghan PG, Henriksen M. Polyacrylamide gel versus hyaluronic acid for the treatment of knee osteoarthritis. A randomised controlled study. Clinical and Experimental Rheumatology. 2024. clinexprheumatol.org
Bagheri K, Shekhar A, Kwok E, et al. Platelet rich plasma compared to viscosupplementation in the treatment of knee osteoarthritis. A systematic review and meta-analysis of randomised controlled trials with 6 month and 12 month follow-up. Journal of Experimental Orthopaedics. 2025. doi.org/10.1002/jeo2.70335
Bennell KL, Paterson KL, Metcalf BR, et al. Effect of intra-articular platelet-rich plasma vs placebo injection on pain and medial tibial cartilage volume in patients with knee osteoarthritis. The RESTORE randomized clinical trial. JAMA. 2021. doi.org/10.1001/jama.2021.19415
This article is for information and does not replace personal medical advice. All treatments at The London PRP Clinic by The Wellness are performed by GMC-registered doctors. Reviewed by a GMC-registered doctor at The London PRP Clinic by The Wellness. Last updated October 2026.
