Two Very Different Approaches to Knee Pain
If you are researching knee injections for osteoarthritis, you have likely encountered two categories of treatment: the established hyaluronic acid (HA) injections that have been used for over 25 years, and the newer Arthrosamid hydrogel injection that has been generating buzz in 2026.
These treatments work through completely different mechanisms. Understanding those differences is essential to making an informed decision about your care.
Quick Comparison Table
| Feature | Arthrosamid | Hyaluronic Acid |
|---|---|---|
| Type | Polyacrylamide hydrogel | Hyaluronic acid gel |
| How it works | Integrates into joint lining | Lubricates joint fluid |
| Injections needed | 1 | 1-5 (varies by brand) |
| Duration of relief | 2-3+ years (early data) | 6-12 months |
| Stays in body | Yes (permanent) | No (absorbed over months) |
| FDA approved (US) | No | Yes (8+ brands) |
| Medicare covered | No | Yes |
| Out-of-pocket cost | $3,000-$5,000 | $50-$200 with insurance |
| Available in US | Clinical trials only | Widely available |
| Years of safety data | ~8 years (EU) | 25+ years |
| Allergy concerns | None (synthetic) | Avian allergy risk (some brands) |
How They Work: The Fundamental Difference
Hyaluronic Acid Injections
HA injections supplement the natural lubricant in your joint. Healthy joint fluid contains hyaluronic acid, which provides lubrication and shock absorption. Osteoarthritis degrades this fluid, making it thin and less protective.
HA injections restore that cushioning by adding a thick, viscous gel to the joint space. The body gradually absorbs this gel over several months, which is why treatments need to be repeated.
Available brands include: Synvisc-One, Euflexxa, Supartz FX, Hyalgan, Monovisc, Durolane, Gel-One, and Orthovisc.
Arthrosamid
Arthrosamid does not lubricate the joint fluid. Instead, it targets the synovial membrane (the tissue that lines the inside of the joint capsule). After injection, the 2.5% polyacrylamide hydrogel migrates to the joint wall and integrates into the tissue over several weeks.
Once integrated, it restores the thickness and elasticity of the joint lining, creating a permanent cushion. Because the hydrogel is non-biodegradable, the body does not break it down, and the effect can potentially last for years.
Duration: Where Arthrosamid Stands Out
The most striking difference between these treatments is how long they last.
Hyaluronic acid: 6 to 12 months per treatment. Most patients need repeat injections once or twice per year. Over 5 years, that could mean 5 to 10 injection series.
Arthrosamid: Early clinical data from the MIVAC trial and open-label studies suggests 2 to 3+ years of relief from a single injection. If this holds up in larger trials, a patient could potentially go years without retreatment.
Important context: Arthrosamid’s duration claims come from smaller studies with limited follow-up. HA injection duration data comes from thousands of patients studied over decades. We need more data before we can confirm Arthrosamid’s long-term performance.
Evidence and FDA Status
Hyaluronic Acid Evidence
- 25+ years of clinical use in the US
- Multiple large randomized controlled trials across all major brands
- FDA-approved since 1997 (Synvisc was among the first)
- Real-world data from hundreds of thousands of patients
- Moderate to strong evidence for pain relief in mild to moderate knee OA
- Well-characterized side effects with no major safety surprises
Arthrosamid Evidence
- MIVAC trial (2023): Randomized, saline-controlled, showed significant pain reduction at 12 months
- 24-month follow-up: Sustained benefit without repeat injections
- Open-label studies: Some patients report relief at 3+ years
- SYMPHONY study: Larger trial designed to strengthen the evidence base
- CE-marked in Europe since 2017
- Not FDA-approved in the United States
The gap in evidence is substantial. HA injections have a track record that Arthrosamid cannot yet match. That said, the early results are genuinely encouraging.
Cost and Insurance: The Practical Reality
For most patients, this is where the decision becomes clear.
Hyaluronic Acid Costs
- With Medicare: Patient pays approximately $50 to $150 per treatment (20% coinsurance)
- With private insurance: Similar range, though prior authorization may be required
- Self-pay: $300 to $1,500 per injection series depending on brand
- Annual cost with insurance: $100 to $300 for 1-2 treatments per year
Arthrosamid Costs
- No insurance coverage: Not FDA-approved, no HCPCS code, no reimbursement possible
- Self-pay only: $3,000 to $5,000 at international clinics
- Additional costs: Travel, lodging, follow-up care coordination
- Total realistic cost: $4,000 to $7,000 including travel to a European clinic
Five-Year Cost Comparison
| Scenario | HA (with Medicare) | HA (self-pay) | Arthrosamid |
|---|---|---|---|
| Year 1 | $150 | $1,000 | $5,000+ |
| Year 2 | $150 | $1,000 | $0 |
| Year 3 | $150 | $1,000 | $0 |
| 5-year total | $750 | $5,000 | $5,000+ |
For patients with insurance, HA injections are dramatically more affordable. For self-pay patients, the math becomes closer if Arthrosamid truly lasts 3+ years.
Safety Comparison
Hyaluronic Acid Safety Profile
- Common: Temporary injection site pain, mild swelling, stiffness (resolves in days)
- Uncommon: Pseudoseptic reactions (Synvisc), joint effusion
- Rare: Infection, allergic reaction (avian-derived products)
- Key advantage: If you do not like the results or experience side effects, the HA is absorbed naturally. Nothing permanent remains in your joint.
Arthrosamid Safety Profile
- Common: Similar temporary pain and swelling at injection site
- Reported: Low adverse event rates in published studies
- Key concern: The hydrogel is permanent. If a problem develops months or years later, it cannot be easily removed from the joint lining.
- Unknown: Very long-term effects (10+ years) of a permanent synthetic implant in the knee
Reversibility Matters
One underappreciated advantage of HA injections is that they are fully reversible. The gel is absorbed by your body within months. If you have a bad reaction or the treatment does not help, there are no lasting consequences. Arthrosamid is permanent, which is both its strength (long duration) and its risk (no take-backs).
Who Should Choose What
Choose Hyaluronic Acid If You:
- Want a proven, FDA-approved treatment backed by 25+ years of data
- Rely on Medicare or private insurance to cover treatment costs
- Prefer a reversible treatment that leaves nothing permanent in your joint
- Have mild to moderate knee OA and want reliable 6-12 month relief
- Value widespread US availability and easy access to experienced providers
- Are trying knee injections for the first time
Consider Arthrosamid If You:
- Have already tried HA injections and found 6-month cycles too short
- Can afford $3,000-$5,000 out of pocket and potential travel costs
- Have an avian allergy that prevents using chicken-derived HA products
- Are comfortable with a newer, less-studied treatment with a permanent implant
- Understand that it is not FDA-approved and accept the regulatory uncertainty
- Want the convenience of a single injection over multi-year periods
Frequently Asked Questions
Can I switch from HA injections to Arthrosamid?
Yes. There is no contraindication to receiving Arthrosamid after previous HA treatment. The two work through completely different mechanisms and do not interact.
Is Arthrosamid just a better version of HA injections?
Not exactly. They are fundamentally different products. Arthrosamid is not an improved hyaluronic acid. It is a different material (polyacrylamide) that works in a different way (integrating into tissue vs. lubricating fluid). Whether it is “better” depends on what matters most to you: proven track record or potential for longer duration.
Why is Arthrosamid not FDA-approved yet?
FDA approval for medical devices like Arthrosamid requires extensive clinical trial data demonstrating both safety and efficacy. The process typically takes years. Contura International is pursuing approval, but the timeline is uncertain as of 2026.
Can I get both treatments at the same time?
This is not recommended and has not been studied. If you are considering Arthrosamid, it would typically be used as an alternative to HA, not alongside it.
What happens if Arthrosamid does not work for me?
Because the hydrogel is permanent, it remains in your joint lining even if you do not experience relief. You could still pursue other treatments, including HA injections, cortisone, physical therapy, or eventually knee replacement surgery.
Which has fewer side effects?
Both have similar short-term side effect profiles (temporary pain, swelling). HA injections have a much longer track record, so their side effect profile is better understood. The long-term effects of Arthrosamid’s permanent implant are still being studied.
The Bottom Line
Proven Today vs. Promising Tomorrow
Hyaluronic acid injections are the right choice for most American patients in 2026. They are FDA-approved, covered by Medicare and most insurance plans, available at thousands of clinics, and supported by one of the strongest evidence bases in orthopedic medicine. They work well for the majority of knee OA patients.
Arthrosamid is a genuinely innovative approach with exciting early data. If long-term studies confirm that a single injection provides years of relief, it could become a preferred option for many patients. But right now, it lacks FDA approval, insurance coverage, US availability, and the decades of safety data that HA injections offer.
Our advice: Start with proven HA injections. If they work for you, continue using them while keeping an eye on Arthrosamid’s progress through the FDA pipeline.
Related Comparisons
- Arthrosamid vs. Synvisc
- HA Injections vs. Cortisone
- PRP vs. Hyaluronic Acid Injections
- Gel Injections vs. Knee Replacement
- Single Injection vs. Series
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