Knee osteoarthritis can turn simple things — climbing stairs, walking the dog, getting out of a chair — into daily battles. Many people try painkillers, physiotherapy and steroid injections, only to find the relief fades within weeks or months. Surgery may feel like the only option left.
An Arthrosamid injection offers another path. It is a single, non-surgical hydrogel injection designed to cushion the knee and ease pain for the long term. In clinical studies, patients reported meaningful pain relief for up to five years after just one treatment.
In this guide, we explain what an Arthrosamid injection is, how it works, who it suits, what to expect on the day and what the evidence really shows — so you can decide whether it is right for you.
What is an Arthrosamid injection?
Arthrosamid is a soft, injectable hydrogel made of about 2.5% cross-linked polyacrylamide and 97.5% water. Unlike most joint injections, it is non-biodegradable — it is not broken down by the body, which is why its effect can last for years rather than months.
How does it work?
Once injected into the knee joint, the gel integrates with the synovium — the soft lining of the joint. It is thought to:
- Cushion the joint, acting as a shock absorber similar to healthy joint tissue
- Support the joint lining, providing a scaffold that helps the synovium function better
- Reduce inflammation and stiffness, easing pain and making movement more comfortable
Because it works with the joint lining rather than simply lubricating the joint, an Arthrosamid injection is usually given as a one-off treatment, rather than a course of repeat injections.
Who is suitable for an Arthrosamid injection?
An Arthrosamid injection may be a good option if you:
- Have been diagnosed with knee osteoarthritis
- Still have knee pain despite painkillers, physiotherapy or weight management
- Found that steroid or hyaluronic acid injections gave only short-term relief
- Want to delay or avoid knee replacement surgery
- Are not suitable for, or not ready for, surgery
It may not be suitable if you have an active infection in or around the knee, a skin condition at the injection site, or have had a knee replacement in that joint. Your suitability is always confirmed at a consultation, where your doctor reviews your symptoms, medical history and any scans.
What happens during an Arthrosamid injection?
The treatment is quick and carried out as an outpatient procedure — no hospital stay or general anaesthetic is needed.
- Consultation — your doctor assesses your knee, reviews your history and confirms that Arthrosamid is right for you.
- Preparation — the skin is cleaned thoroughly and a local anaesthetic may be used to keep you comfortable.
- Ultrasound-guided injection — using ultrasound, the doctor guides the needle precisely into the knee joint and injects the gel (typically 6 ml in clinical studies). Ultrasound guidance helps make sure the gel reaches the right place.
- Home the same day — most people walk out of the clinic and return to everyday activities soon afterwards.
Recovery and aftercare
Some people notice mild swelling, warmth or soreness in the knee for a few days. This usually settles on its own. Your doctor may advise avoiding strenuous exercise for a short time after the injection.
Pain relief is usually gradual. Many patients notice improvement within the first few weeks, with benefits continuing to build over the following months.
How long does an Arthrosamid injection last?
The strongest evidence comes from a Danish clinical trial that followed patients for five years after a single 6 ml Arthrosamid injection (Clinical and Experimental Rheumatology).
- At five years, patients’ knee pain scores (WOMAC pain) had improved by an average of 16.2 points — well above the 9-point change considered clinically meaningful.
- Stiffness, physical function and patients’ own rating of their knee also improved significantly.
- Improvements were seen across different body weights and severities of osteoarthritis.
It is fair to note the study’s limits: the five-year phase had no comparison group, many participants left the study over time, and it was funded by the manufacturer. Results vary from person to person, and some patients in the study still went on to have knee replacement surgery. Even so, for a single injection, five-year data is unusually long-term evidence.
Arthrosamid vs other knee injections
| Arthrosamid injection | Steroid injection | Hyaluronic acid injection | |
|---|---|---|---|
| What it is | Non-degradable hydrogel | Anti-inflammatory steroid | Lubricating gel |
| Number of injections | Usually one | Can be repeated, with limits | Single or a short course |
| Typical duration of relief | Studied up to 5 years | Weeks to a few months | Up to around 6 months |
| Broken down by the body | No | Yes | Yes |
Steroid and hyaluronic acid injections still have an important role, and may be quicker or cheaper options for some people. An Arthrosamid injection is often considered when these treatments no longer give lasting relief. Your doctor can help you weigh up the options.
Arthrosamid side effects and safety
Most side effects of an Arthrosamid injection are mild and short-lived. The most common are:
- Knee pain or soreness after the injection
- Mild swelling or a feeling of fullness in the knee
These usually settle within a few days. In the five-year study, no serious side effects were linked to the gel itself. As with any injection into a joint, there is a small risk of infection, which is why the procedure is performed in a sterile, clinical setting.
Contact your clinic straight away if you develop increasing pain, redness, heat or a fever after your injection.
Frequently asked questions
Is an Arthrosamid injection painful?
Most patients describe it as similar to other joint injections — a brief pressure or discomfort. Local anaesthetic and ultrasound guidance help keep it as comfortable as possible.
How many Arthrosamid injections will I need?
Usually just one. Because the gel is not broken down by the body, it is designed as a single, long-lasting treatment.
When will I feel the benefit?
Relief tends to build gradually. Many people notice a difference within a few weeks, with further improvement over the following months.
Can Arthrosamid help me avoid knee replacement?
It can help many people delay surgery by reducing pain and improving movement. It does not regrow cartilage, and some people will still need a knee replacement in the future.
Is Arthrosamid available on the NHS?
It is not widely available on the NHS, so most patients have it privately. See our pricing page for current costs.
Can I drive home after the injection?
Most people can, but it is sensible to check with your doctor on the day.
Arthrosamid injection in London at Joint Injection UK
If knee pain is holding you back and other treatments have stopped working, an Arthrosamid injection could help you move more freely — with a single, ultrasound-guided treatment and no surgery.
At Joint Injection UK, your Arthrosamid injection is carried out by Mr Syed Nadeem Abbas, a GMC-registered doctor with nearly 25 years of experience in musculoskeletal medicine. Every patient starts with a thorough consultation to make sure the treatment is right for them, and is followed up afterwards.
Book your consultation today — book online or call +44 7955 836986. You can also explore our other joint injection treatments.
This article is for general information and is not a substitute for personal medical advice. Results vary between individuals.
