Arthrosamid® for Knee Osteoarthritis: Patient Information
Knee osteoarthritis can be managed through different medical and non-surgical approaches. The appropriate option depends on symptoms, medical history, imaging findings, previous treatments and individual circumstances. Arthrosamid® is one of several options a doctor may discuss. Following medical assessment, the physician will explain the options considered appropriate for each patient.
What is Arthrosamid®?
Arthrosamid® is an injectable polyacrylamide hydrogel, often shortened to iPAAG, used in the management of symptomatic knee osteoarthritis. It is composed of 2.5% cross-linked polyacrylamide and 97.5% water and is manufactured by Contura.
Arthrosamid® is a CE-marked medical device regulated under EU Regulation 2017/745 (MDR). It is not a medicine, and it does not contain a steroid or an anti-inflammatory drug.
It is licensed for the knee only and is administered by a doctor after a medical assessment. It is one option among several, and it is not appropriate for everyone.
How is Arthrosamid® thought to work?
On injection, the hydrogel is reported to integrate into the synovial tissue of the inner joint capsule, adhering to the synovial membrane that lines the knee. Rather than sitting loose in the joint fluid, it is thought to become incorporated into the tissue at the inner surface of the capsule.
The hydrogel is non-absorbable, non-biodegradable and non-migratory: it is not broken down by the body and it stays where it is placed.
The exact mechanism by which this may reduce pain is still being studied. Proposed explanations include a cushioning effect at the joint capsule and changes in the synovial lining, but these are not settled, and it would be inaccurate to present any one explanation as established fact.
Is Arthrosamid® permanent?
Yes. The hydrogel does not break down and is not absorbed by the body. Once injected, it remains in the knee and cannot simply be dissolved or withdrawn. This is an important consideration rather than a benefit, and it should be understood clearly before any decision is made.
Permanence of the material is not the same as permanence of symptom relief. The duration of any improvement varies between individuals, and studies report a range of outcomes rather than a uniform result.
Because the material cannot be removed easily, patient selection matters more here than with an absorbable treatment. This is why the assessment before treatment is thorough and why the procedure is not offered to everyone who asks for it.
Who may be considered for Arthrosamid®?
Arthrosamid® is generally considered for adults with symptomatic osteoarthritis of the knee whose pain has not been adequately managed by measures such as physiotherapy, weight management, activity modification or oral pain relief.
In practice, the patients most often assessed as suitable are those with a confirmed diagnosis of knee osteoarthritis supported by recent imaging, ongoing pain that affects daily activity, and no active infection in or around the joint.
Suitability is always decided by the treating doctor after an individual medical assessment, taking account of the state of the joint, your medical history and your individual circumstances.
Who is not suitable for Arthrosamid®?
Arthrosamid® is not appropriate for anyone with an active infection in or near the knee, an infection elsewhere in the body that could reach the joint, or a known sensitivity to any component of the product. In these situations it must not be given.
It is also not used where the problem is not knee osteoarthritis. Pain arising from another joint, from the spine, from a tendon or from an inflammatory arthritis is a different clinical picture and calls for a different approach. It is licensed for the knee only.
Pregnancy, planned imminent knee surgery and certain immune conditions are also reviewed during the assessment.
According to the manufacturer's Instructions For Use, Arthrosamid® must not be injected in the following circumstances:
- There is active skin disease or infection at or near the injection site.
- The joint is infected or severely inflamed.
- The patient has previously received a different non-absorbable injectable or implant.
- The patient has had a knee arthroplasty or has any foreign material in the knee.
- The patient has had a knee arthroscopy in the last six months.
- The patient has haemophilia or is receiving uncontrolled anticoagulant treatment.
What happens during the procedure?
The appointment usually takes around 30 minutes. It consists of a check of the knee, cleaning and local anaesthetic, then the injection, followed by a short period of observation before you go home. It is given as one injection into the knee.
Before that appointment there is a medical assessment, a review of your history and of recent imaging of the knee, and confirmation that the procedure is appropriate.
On the day, arrange for someone else to drive you home. Plan to rest the knee for the first few days. You will be given written aftercare guidance and a point of contact, and a follow-up is arranged so your response can be reviewed.
Risks, side effects and limitations
Temporary pain and swelling at the injection site can occur after an intra-articular injection. Stiffness or warmth around the knee may also occur in the days that follow. As with any injection into a joint, there is also a risk of bleeding, of a reaction to the local anaesthetic, and of infection.
Infection deserves particular attention. Infection in a joint that contains a non-absorbable implant is a more serious complication than infection after a treatment that is absorbed, because the material cannot simply be cleared by the body. This is one of the reasons active infection anywhere in the body must be excluded before treatment.
If removal of the hydrogel were medically necessary, surgery such as synovectomy could be required, and that is not a simple, complete or risk-free procedure.
There is also the possibility of no meaningful improvement: research has identified that a proportion of patients do not respond. Long-term data are more limited than for older, established options. All risks and limitations are explained in full before you consent.
Can I still have a knee replacement later?
Having had Arthrosamid® does not in itself rule out a future knee replacement. Ten-year follow-up data reported surgical records from subsequent knee replacements showing no indications of unusual adverse reactions in the patients concerned.
That is a factual account of what was reported in follow-up, not a guarantee about any individual case. Suitability for future surgery is assessed individually by the surgeon at the time.
It is sensible to tell any surgeon or radiologist that you have had a non-absorbable intra-articular hydrogel injected into the knee, so that imaging is interpreted correctly and the operative plan accounts for it.
What does the research show?
Research on Arthrosamid® is ongoing. The treating doctor will explain the available evidence and its limitations during the consultation.
Other options for knee osteoarthritis
Knee osteoarthritis can be managed in several ways, and injections are only one part of the picture. Depending on the individual situation, a doctor may discuss exercise and physiotherapy, weight management, pain relief medication, other injection options, and surgery where it is indicated. No single option is right for everyone, and the appropriate choice depends on your symptoms, imaging findings and medical history.
You can read more about causes, assessment and non-surgical options on our knee pain page.
Frequently Asked Questions
Common questions about this treatment
Important Medical Disclaimer
This content is informative. Results may vary between patients and the treatment requires prior medical assessment.
Medically reviewed by Dr. Arvin Yarollahi, Specialist in Orthopaedic Surgery and Traumatology. Last reviewed .
Dr. Arvin Yarollahi
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