Knee Injection Comparison
Arthrosamid® vs
Hyaluronic Acid
Two injectable options for knee osteoarthritis with very different mechanisms, duration and treatment patterns. Here is the honest comparison from London Cartilage Clinic.
Reviewed byProf Paul Lee MBBch, FRCS (Tr & Orth), PhDLast reviewed 1 May 2026Quick Answer
Hyaluronic acid is a resorbable joint lubricant that typically lasts around six months and often requires repeat injections. Arthrosamid® is a non-resorbable polyacrylamide hydrogel designed for long-acting symptom control from a single injection, with published outcome data showing on average two to three years of relief in suitable patients. Hyaluronic acid may still be the right first step for some patients; Arthrosamid® is generally the more durable option where suitability is confirmed at consultation.
The Headline Difference
Arthrosamid® vs Hyaluronic Acid — the key difference
The biggest difference is what the body does with the injection. Hyaluronic acid is reabsorbed by the joint over months. Arthrosamid® is a permanent hydrogel that integrates into the synovial membrane and stays in place. That mechanism is what gives Arthrosamid® its multi-year duration — and it is also why patient selection and infection-prevention protocol matter more for Arthrosamid® than for hyaluronic acid.
Mechanism of Action
How each treatment works
Arthrosamid® is a polyacrylamide hydrogel injected into the knee joint under ultrasound guidance. The gel integrates into the synovial membrane, acting as a long-term cushion and lubricant. It is not absorbed, not metabolised and not regenerative; it works mechanically rather than biologically.
A single injection is the typical treatment course in suitable patients.
Hyaluronic acid (HA) is a viscous lubricating substance naturally found in joint fluid. Injected forms are usually derived from bacterial fermentation. HA injections replace and supplement the joint’s lubricating fluid for a period of weeks to months before being reabsorbed by the body.
Common UK brands include Durolane (single-dose) and Monovisc, alongside multi-dose regimens that require three to five weekly injections.
How Long Results May Last
Duration and number of injections
2 to 3 years
Around 6 months
Duration figures are averages from published data; not a guarantee for any individual case. Outcomes are confirmed and discussed in writing at consultation.
Treatment Course
Number of injections
One injection is the standard treatment course. Most patients are treated with a single box of Arthrosamid® per joint. Two or three boxes are used where multiple joints are treated in the same session, or where a larger joint requires additional volume.
Single-dose HA preparations (e.g. Durolane) require one injection. Older multi-dose preparations require three to five weekly injections per treatment course. Many patients repeat the course every six to twelve months for ongoing benefit.
Safety and Infection
Safety considerations
Both treatments are delivered under ultrasound guidance at London Cartilage Clinic. The most serious risk for either is joint infection, which is rare but warrants a conservative prevention protocol.
Arthrosamid® carries a slightly different risk profile because the hydrogel is permanent — a late infection is harder to manage than for resorbable injections. This is why we use routine IV antibiotic cover for Arthrosamid® specifically. For hyaluronic acid the antibiotic decision is made on a case-by-case basis.
See Arthrosamid® infection risk and prevention and Arthrosamid® side effects and safety for the full picture.
Patient Selection
Who each treatment may suit
Hyaluronic acid is often used as a first-line or repeat-injection option for milder knee osteoarthritis where short-to-medium-term symptom control is the goal. Arthrosamid® tends to suit patients who have already tried conservative options or HA, want longer duration from a single injection, and are looking to delay more invasive treatment.
Neither treatment is a substitute for knee replacement where replacement is clinically appropriate. See who is suitable for Arthrosamid? for the full suitability framework.
Cost and Value
What each treatment costs
At London Cartilage Clinic, Arthrosamid® costs from £3,000 for one box, inclusive of consultation, ultrasound, the product, the fifteen-step injection protocol and the six-week follow-up. See the Arthrosamid® cost guide for two- and three-box pricing.
Hyaluronic acid injection pricing depends on the brand, the number of doses required and whether ultrasound guidance is used. Multi-dose courses cost more in total than the headline single-injection price. The total cost over two to three years can be similar to or higher than a single Arthrosamid® treatment if repeat HA courses are needed.
Our Honest Take
When we may recommend each
You have established knee osteoarthritis with mild-to-moderate cartilage wear.
You have tried conservative treatment or HA and want longer-acting symptom control from a single injection.
You want to delay more invasive surgery when appropriate, with realistic expectations and willingness to accept the safety protocol.
You are at an earlier stage of osteoarthritis and a shorter-duration option is acceptable.
You want to try a resorbable injection before committing to a permanent hydrogel.
You have a clinical or personal reason to avoid permanent intra-articular implants.
When Each Is The Wrong Answer
When we would not recommend each
End-stage bone-on-bone arthritis where Arthrosamid® is unlikely to deliver meaningful benefit.
Active infection or unwillingness to accept the conservative safety protocol.
Unrealistic expectation of cure, cartilage regeneration or guaranteed permanent relief.
Patients who want a single, multi-year intervention rather than repeat courses.
Where prior HA has not delivered useful benefit, repeating may not be the right next step.
End-stage arthritis where neither injection is likely to defer the need for replacement.
The Bottom Line
In summary
In suitable patients with mild-to-moderate knee osteoarthritis, Arthrosamid® offers longer duration from a single injection than hyaluronic acid, at the cost of permanence and a more conservative safety protocol. Hyaluronic acid remains a reasonable shorter-duration choice, especially as a first-line or repeat option. The right answer for any individual is decided at consultation with imaging review.
Arthrosamid® vs Hyaluronic Acid
Frequently asked questions
Can I have Arthrosamid® if I have already had hyaluronic acid?
Yes, in most cases. Prior hyaluronic acid is not a contraindication to Arthrosamid®. We typically wait until the previous HA injection effects are no longer the dominant variable, but each case is decided on the imaging and clinical picture at consultation.
Is Arthrosamid® more effective than hyaluronic acid?
Direct head-to-head comparisons are limited, but the published evidence suggests Arthrosamid® delivers longer-duration symptom control from a single injection than hyaluronic acid in suitable patients. “More effective” depends on what you are optimising for — duration, single-visit convenience, or first-line conservative management.
Is hyaluronic acid available on the NHS in the UK?
Hyaluronic acid is available on a limited basis through some NHS pathways but is not routinely commissioned everywhere. Arthrosamid® is not routinely funded by the NHS. Both are accessed privately at London Cartilage Clinic.
Can I switch from hyaluronic acid to Arthrosamid® if HA stops working?
Yes, this is a common reason patients consider Arthrosamid®. We will review imaging and confirm suitability — Arthrosamid® is not right for every patient, but a diminishing response to HA is a reasonable reason to discuss alternatives.
Does hyaluronic acid regenerate cartilage?
No. Hyaluronic acid is a joint lubricant. It supplements the natural fluid in the joint but does not regenerate cartilage tissue. Neither does Arthrosamid®. Both treat symptoms rather than underlying disease.
Book an Arthrosamid® Assessment – London
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Learn More about Arthrosamid
Deep dive into our clinical resources and patient guides.
Cost in the UK
Arthrosamid® cost in the UK from £3,000, what is included and why prices vary.
NHS & Insurance
Is Arthrosamid® available on the NHS or private insurance?
Suitability
Who is suitable for Arthrosamid® — and who may need caution.
Clinical Evidence
Real-world outcome data and what the evidence means for patients.
Side Effects & Safety
Arthrosamid® side effects, risks, complications and clinical context.
Infection Risk
Arthrosamid® infection risk, prevention protocol and IV antibiotic policy.
In London
Private Arthrosamid® treatment at our Harley Street clinic.
Self-Assessment
Eight-question Arthrosamid® suitability self-assessment tool.
Full FAQ
Arthrosamid® patient FAQ across cost, suitability, safety and comparisons.
vs Hyaluronic Acid
Arthrosamid® compared to hyaluronic acid injections.
vs PRP
Arthrosamid® compared to PRP for knee osteoarthritis.
vs Steroid Injection
Arthrosamid® compared to corticosteroid injection.
vs Knee Replacement
Where Arthrosamid® may help delay surgery — and where it cannot.
Arthrosamid® Injection
Comprehensive Overview
Arthrosamid® is a registered trademark of Contura A/S. London Cartilage Clinic is not affiliated with or endorsed by Contura A/S.