Patients under 70 reported close to 80% positive response⁷Data on file. following treatment with Arthrosamid.

Response rate based on change from baseline in WOMAC pain scores.

What is the response rate of Arthrosamid?

Non-biodegradable hydrogel: the key innovation

Arthrosamid is composed of 97.5% water and 2.5% cross-linked polyacrylamide, a biocompatible polymer used safely in medical devices for decades. The cross-linked structure gives it viscoelastic properties: it is flexible under shear stress but maintains its form under load. Critically, it is non-biodegradable, meaning the body does not break it down over time. This distinguishes it fundamentally from hyaluronic acid, which degrades within 6 to 12 months.

How it works inside the knee

In a healthy knee, synovial fluid provides lubrication and shock absorption. Osteoarthritis reduces both the volume and viscosity of this fluid, leading to increased friction and bone stress. Arthrosamid is injected under ultrasound guidance into the synovial space, where it integrates with the synovial membrane lining. Once integrated, it restores the cushioning layer within the joint, reducing pain signals and improving load distribution during movement.

Arthrosamid compared to other treatments

Hyaluronic acid injections provide temporary viscosupplementation lasting 6 to 12 months, requiring repeat treatment annually. Corticosteroid injections reduce inflammation for 4 to 12 weeks but carry tissue degradation risk with repeated use. Arthrosamid requires a single injection, is supported by clinical trial data demonstrating sustained improvement for up to 5 years³⁷˒⁴²Clinical trial data showing sustained improvement up to 5 years after single Arthrosamid injection., and does not require retreatment.

Well-suited candidates: mild to moderate knee osteoarthritis

Patients most likely to benefit are those with Kellgren-Lawrence grade 2 or 3 osteoarthritis, aged 40 to 75, whose pain is limiting daily activities despite conservative management. Candidates who have received limited benefit from hyaluronic acid injections, or who are not yet ready for joint replacement surgery, are typically good candidates. Published data suggests a positive response rate of close to 80% in patients under 70 years of age.⁷Data on file.

Cases considered on an individual basis

Patients with early-stage osteoarthritis (grade 1) and minimal functional limitation may achieve adequate benefit from conservative measures alone. Those with severe grade 4 osteoarthritis may still benefit from Arthrosamid but should be counselled that joint replacement may ultimately be required. Patients with bilateral knee osteoarthritis can be treated, with procedures staged 6 to 8 weeks apart.

Patients for whom Arthrosamid is not appropriate

Arthrosamid is not indicated for patients with active knee infection, confirmed allergy to polyacrylamide, or those who are pregnant or breastfeeding. Patients with severe limb malalignment requiring osteotomy, or those for whom knee replacement surgery has been clinically recommended and is appropriate, should be directed to the relevant surgical pathway. Treatment with Arthrosamid may not be suitable for everyone. Your doctor is the best person to advise you.

From £2,800

London pricing per knee

At Dr SNA Clinic, Arthrosamid injection starts from £2,800 per knee, including ultrasound-guided administration and post-procedure follow-up. An initial consultation fee applies and is redeemable against the cost of treatment. Bilateral treatment is available, with procedures staged to allow appropriate recovery between sessions.

Private medical insurance

Arthrosamid injections are currently available on a self-funding basis. Some UK private medical insurers may provide cover where treatment has been recommended by a consultant. Patients are advised to contact their insurer directly to confirm eligibility prior to booking. Dr SNA Clinic provides itemised invoices to support insurance submissions where applicable.

Cost in context

Hyaluronic acid injections require repeat treatment on an annual basis, with cumulative costs that may equal or exceed the cost of a single Arthrosamid injection within a few years. Private knee replacement surgery in the UK typically costs from £12,000 to £15,000, with a recovery period of 6 to 12 months. For eligible patients, Arthrosamid may reduce or delay the need for surgical intervention, representing meaningful clinical and financial value over time.

Clinical trial data: up to 5 years follow-up

Arthrosamid has been studied across multiple independent clinical studies. In all studies, improvement in WOMAC pain scores exceeded the minimum clinically important difference (MCID) of 9 points¹⁶Minimum clinically important difference (MCID) of 9 points on WOMAC pain subscale.. Pain reduction was maintained for up to 5 years following a single injection. Arthrosamid remains safe and effective for its intended use 5 years after treatment. Individual results may vary.

What patients report

In clinical follow-up, patients commonly describe improvements in their ability to walk longer distances, manage stairs, and return to light recreational activity. Sleep disturbance related to knee pain is frequently reported as reduced. Outcomes vary between individuals. Arthrosamid is intended to manage the symptoms of osteoarthritis rather than reverse or cure the underlying condition. Patients are counselled on realistic expectations prior to treatment.

Understanding the non-responder rate

Not all patients experience significant improvement following Arthrosamid injection. Non-response is more commonly observed in patients with severe joint malalignment, significant meniscal pathology, an inflammatory arthritis component, or pain that is not primarily mechanical in origin. Thorough pre-treatment assessment is designed to identify patients most likely to benefit and to direct others towards more appropriate treatment pathways.

PRP for Knee Osteoarthritis

Platelet-rich plasma (PRP) therapy uses a concentration of the patient's own blood platelets to support tissue repair and reduce joint inflammation. It is a less invasive and lower-cost option than Arthrosamid, with a course typically involving 3 to 6 injections over several months. PRP may be considered as a first-line injectable treatment before progressing to Arthrosamid in appropriate cases.

Why: A suitable option for patients seeking an entry-level injectable treatment with regenerative potential.

Stem Cell Therapy for Joints

Adipose-derived mesenchymal stem cell therapy involves harvesting fat cells and processing them into a concentrated regenerative injection for the knee. It is a more involved procedure than Arthrosamid but may offer greater tissue regeneration potential for younger patients with moderate to severe osteoarthritis. Pricing starts from £6,000.

Why: Considered for patients under 55 seeking a regenerative approach rather than structural support alone.

Adipose Cell Therapy

Adipose cell therapy uses fat-derived regenerative cells to reduce joint inflammation and support tissue repair. It offers a minimally invasive alternative to bone marrow-derived procedures and may be combined with Arthrosamid in selected patients to address both structural support and active inflammation.

Why: May be considered where both joint cushioning and inflammation management are clinical priorities.