Arthrosamid Injection in London: A Complete Guide

Osteoarthritis is the most common form of arthritis in the knee. It increasingly affects younger people. Treatment options include exercise, weight loss, medication, injections, and knee replacement. Arthrosamid — a non-degradable hydrogel — now offers longer-lasting pain relief than other injections for many patients.

Dr Masci performs Arthrosamid injections at his London clinics for £2,500, all-inclusive. This price is significantly below that of most other UK centres. He has over 15 years of experience in ultrasound-guided injections and teaches these techniques to doctors across the UK and Europe. This guide explains what Arthrosamid is, the evidence behind it, the procedure, and the cost. 

What causes knee osteoarthritis pain?

Osteoarthritis wears away the knee’s shock-absorbing cartilage. This leads to bone-on-bone contact, inflammation, stiffness, and pain. Importantly, the pain comes mostly from joint inflammation rather than the cartilage wear itself. Arthrosamid targets this inflammation directly.

Treatment options for knee osteoarthritis

Exercise therapy and weight loss remain the most effective treatments. Medications such as ibuprofen also help. For more severe cases, we use injections into the knee joint. Common options include cortisone, hyaluronic acid, and PRP. Arthrosamid now offers a longer-lasting alternative to these established injections.

What is Arthrosamid?

Arthrosamid is a hydrogel. It consists of 97.5% water bound to a 2.5% polyacrylamide backbone. The gel is non-degradable, which means the body cannot break it down. This property gives Arthrosamid its long-lasting effect.

Doctors have used this hydrogel for over 20 years as a bulking agent in conditions such as stress incontinence. Vets have used it extensively in horses with arthritis since 2009, and doctors first used it in human joints in 2010. Biological studies show Arthrosamid is inert. It does not react with muscle, bone, or joint tissue. Clinicians have performed more than 26,000 Arthrosamid injections in Europe and the UK since its approval in 2020.

How does Arthrosamid gel work?

The synovium is a thin membrane lining the joint. Its cells produce the fluid that lubricates the knee. When we inject Arthrosamid gel into the joint, synovial cells take it up and form a new joint lining. This new lining reduces inflammation, which in turn reduces pain. The process takes up to four weeks.

What does the evidence show? 

arthrosamid studies

The evidence base for Arthrosamid continues to grow. Early studies from 15 years ago showed excellent results from 4 weeks through 26 weeks. Follow-up studies showed the effect persisted for years.

A randomised controlled trial compared Arthrosamid with hyaluronic acid in knee arthritis. Both improved symptoms at one year. However, Arthrosamid performed better in younger, slimmer patients and in those with a large effusion. The overall positive response rate reached 73%, and age strongly influenced the result:

  • Under 60 years: 94% response rate
  • Under 70 years: 80% response rate
  • Over 70 years: 63% response rate

Pain relief typically begins at 4 weeks and peaks at around 12 weeks. A recent study from Turkey suggests the maximum effect can take up to six months. On average, patients improve by 20–25% in pain and function. Crucially, long-term RCT data show the benefit lasts at least five years. Hyaluronic acid and PRP, by comparison, last around a year.

A further RCT compared Arthrosamid with Synvisc-1 (a hyaluronic acid). Patients with knee swelling responded better to Arthrosamid at 6 months. In our experience, patients with an inflamed, swollen knee do particularly well with Arthrosamid gel.

How does Dr Masci perform an Arthrosamid injection?

Accuracy decides the outcome. Without imaging, knee injections reach the joint only 50–80% of the time. That means up to one in three blind injections misses the target — a costly miss with a £2,500 product. Dr Masci performs every Arthrosamid injection under ultrasound guidance, which delivers close to 100% accuracy.

The procedure follows clear steps. Dr Masci numbs the skin with a local anaesthetic. If the knee carries significant swelling, he drains it first. He then guides the needle into the joint under ultrasound and injects the gel using a sterile technique. The video below shows Dr Masci performing the injection.

[VIDEO: keep existing video embed — Dr Masci performing ultrasound-guided knee injection]

Dr Masci has performed thousands of ultrasound-guided procedures. He teaches advanced injection techniques to doctors and physiotherapists across the UK and Europe, and publishes research on injection therapy. You can read more about his injection expertise here.

What should you expect after the procedure?

We observe you for 15 minutes after the injection. You may feel tightness or mild pain once the anaesthetic wears off. Continue your regular medications and painkillers. Arthrosamid feels denser than other injectables, so the sensation may differ from injections you have had before.

Side effects of Arthrosamid injections

Patients tolerate this implant well. The most common side effect is pain at the injection site. The knee may also feel full or distended, and a Baker’s cyst can swell. This flare affects around 20% of patients, stays mild, and settles within 2–4 weeks. We manage it with relative rest, ice, and anti-inflammatories such as ibuprofen.

Serious side effects are rare. Reported rates of suspected infection sit at around 0.02% — a handful of cases across tens of thousands of injections. As a precaution, we give prophylactic antibiotics at the time of injection. Because the gel is non-degradable, a high antibiotic concentration at injection further reduces the risk of infection.

How much does an Arthrosamid injection cost in London?

Dr Masci performs Arthrosamid injections for £2,500, all-inclusive. This covers the ultrasound-guided procedure with one of the UK’s most experienced injection specialists. Most other London and UK centres charge considerably more for the same product — often without ultrasound guidance as standard.

UK private insurance does not currently cover Arthrosamid, so all patients self-fund. Dr Masci also treats patients travelling from overseas, including the USA and Canada, where Arthrosamid is not yet available. Our clinic locations are here, and you can contact the team here to book.

Who responds best to Arthrosamid?

From our experience, the best candidates include:

  • Patients with patellofemoral osteoarthritis who want to avoid surgery
  • Those who tried other injections without lasting relief
  • Patients too young for a knee replacement — under-70s show an 80%+ response rate
  • People who want to stay active
  • Patients with knee swelling or pain after activity

Not everyone improves. Around 5–20% of patients see no benefit or feel worse, a rate similar to other injectables. We discuss this honestly at your consultation before you commit.

Frequently asked questions about Arthrosamid

How long does Arthrosamid take to work?

Pain relief usually starts at four weeks. The maximal effect generally arrives at 3 months, though a recent study suggests it can take up to six months. Some patients notice improvement within two weeks.

How long does Arthrosamid last?

A 2025 study shows the benefit lasts at least 5 years. Patients under 70 respond better than those over 70. This compares favourably with hyaluronic acid and PRP, which last around a year.

Is Arthrosamid gel a type of hyaluronic acid?

No. The body rapidly degrades hyaluronic acid. Arthrosamid hydrogel is non-degradable, so it remains in the knee joint and lasts longer.

When can you return to sport after an Arthrosamid gel injection?

Rest the knee from exercise for around 10 days. Short-term rest reduces the chance of a flare. A typical return to running looks like this:

  • Day 1: complete rest, ice, and ibuprofen for pain
  • Day 2: upper body weights and swimming without kicking
  • Days 3–7: add light kicking and light cycling
  • Days 7–10: start lower body weights at 50% intensity
  • Day 14: return to running, guided by pain

Are there any contraindications?

We do not inject Arthrosamid if you have: active skin or joint infection; a recent cortisone, hyaluronic acid, or PRP injection that has not yet degraded; a knee replacement (metal in the joint); knee arthroscopy within six months; infection in another joint; or inflammatory arthritis such as psoriatic arthritis. We also do not treat minors or pregnant women.

I’ve just had a Durolane injection. Do I have to wait?

Yes. Wait 3 months for the Durolane to fully degrade before having Arthrosamid.

Can Arthrosamid be injected without imaging?

Yes, but we strongly advise against it. Blind knee injections reach the joint only 60–80% of the time. Ultrasound guidance delivers close to 100% accuracy. With a £2,500 product, accuracy matters. Always confirm that your doctor uses an ultrasound.

Can I have both knees treated?

Yes. We space the injections at least 1 week apart rather than treating both knees in one visit.

Can I have a top-up injection?

Yes, if you had a partial response. Wait around 6 months first, as Arthrosamid can take that long to reach full effect. Top-ups use 3 mL rather than the initial 6 mL.

Can you have a knee replacement after Arthrosamid?

Yes. Safety data extend roughly 15 years, including 90 knees that went on to replacement with no reported problems during or after surgery. About 10% of Arthrosamid patients later undergo knee replacement.

Do diabetes or obesity change the response?

Diabetes reduces effectiveness by roughly 10%, but it is not a contraindication. Obese patients respond similarly to non-obese patients, and weight loss further helps with pain.

Can people with active cancer have Arthrosamid gel?

Yes. Unlike PRP, active cancer does not contraindicate Arthrosamid.

Is Arthrosamid available on the NHS?

No. Several NHS trusts are running studies so that you can contact your local trust for details.

When will Arthrosamid be available in the USA?

Contura has applied for FDA approval, as well as approval in Canada and Australia. The timeline remains uncertain. In the meantime, Dr Masci treats patients who travel to London from the USA and Canada.

Final word from Sport Doctor London about Arthrosamid

Could Arthrosamid be a game changer for stubborn knee arthritis? Potentially, yes. Consider it if exercise, weight loss, and other injections such as Durolane or PRP have not worked. Understand that not every patient improves — we select candidates carefully and advise you honestly.

Dr Masci offers ultrasound-guided Arthrosamid injections in London for £2,500 — significantly less than most other UK centres. He also welcomes patients from the USA and Canada. Contact his dedicated team here or call +44 (0) 203 488 0350.

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