Hymovis for Knee Osteoarthritis: Complete Patient Guide

What Is Hymovis?

Hymovis is a hyaluronic acid (HA) injection for knee osteoarthritis that stands out with its unique 2-injection protocol—fewer visits than traditional 3- or 5-shot treatments, but more gradual than single-injection options like Synvisc-One.

Developed by Fidia Pharma USA, Hymovis uses HYADD4 technology to create a biofermented HA that’s safe for patients with bird allergies. If you’ve been told other gel shots aren’t an option due to egg or poultry allergies, Hymovis may be your answer.

Each injection delivers 24mg of high molecular weight hyaluronic acid (molecular weight 500-730 kDa), administered one week apart. This “middle ground” approach offers a balance between convenience and gradual symptom improvement.

Quick Facts About Hymovis

Is Hymovis Right for You?

Hymovis may be a good fit if you:

• Want fewer appointments than 3-shot brands (Euflexxa, Supartz)
• Have bird, egg, or poultry allergies that make avian-derived products risky
• Prefer gradual onset over the single-shot approach (Synvisc-One, Gel-One)
• Have mild-to-moderate knee osteoarthritis (Kellgren-Lawrence grades 2-3)
• Haven’t responded well to oral medications or physical therapy alone
• Want to delay surgery while maintaining mobility
• Value proven technology (HYADD4 used in Europe since 2009)

Not ideal if you:

• Need the absolute fewest possible injections (consider Synvisc-One or Monovisc)
• Require the longest-studied brand (Synvisc has more long-term data)
• Want the lowest-cost option (Supartz FX may be cheaper)
• Have severe, end-stage osteoarthritis (surgery may be more appropriate)

HYADD4 Technology: What Makes Hymovis Different

Hymovis uses HYADD4 (Hyaluronic Acid Auto-Cross-Linked Polysaccharide) technology—a proprietary process that creates “hybrid cooperative complexes.”

How HYADD4 Works

Unlike chemically cross-linked gels (Synvisc) or linear HA chains (Supartz), HYADD4 creates a network of HA molecules that work together through natural associations. Think of it as HA molecules holding hands rather than being tied together with chemical bonds.

Benefits of this approach:

• Better integration with your natural joint fluid
• Gradual release as the gel breaks down naturally
• Maintained viscosity even as the product degrades
• No chemical cross-linking agents (potentially fewer reactions)

The Science

Research published in Cartilage (2016) showed that HYADD4 demonstrated:

• Superior rheological properties (flow and cushioning)
• Longer residence time in the joint compared to linear HA
• Protective effects on cartilage cells in laboratory studies

The high molecular weight (500-730 kDa) mimics healthy, youthful joint fluid better than lower molecular weight alternatives.

The 2-Visit Protocol

Hymovis’s defining feature is its 2-injection schedule—unique among FDA-approved viscosupplements.

Treatment Timeline

Week 1: First Injection

• Provider cleans and numbs injection site
• Fluoroscopic guidance recommended (not required)
• 2mL injection into knee joint space
• 15-minute procedure, minimal downtime
• Light activity same day, resume normal activity within 48 hours

Week 2: Second Injection

• Same process as first visit
• Most patients report less anxiety than visit 1
• Cumulative effect begins building

Weeks 3-12: Gradual Improvement

• Many patients notice relief by week 4-6
• Peak benefit typically at 8-12 weeks
• Effect continues 6-12 months on average

Why Two Injections?

The 2-dose protocol provides:

• Higher total HA volume than single-shot brands (4mL vs 6mL)
• More gradual onset which some patients prefer
• Fewer visits than 3-shot protocols (Euflexxa, Supartz)
• Flexibility to adjust second dose timing if needed

Effectiveness: What Research Shows

Clinical Trial Results

The pivotal FDA trial (published in Journal of Orthopaedic Surgery and Research, 2016) compared Hymovis to saline placebo in 672 patients:

• 52% of Hymovis patients achieved 20mm+ improvement on pain scale vs. 37% placebo
• Benefits lasted 6 months in majority of responders
• Responder rate higher in patients with mild-moderate OA vs. severe
• Safety profile similar to placebo (no serious adverse events)

Real-World Outcomes

Post-market studies suggest:

• 6-12 months average symptom relief
• 60-70% patient satisfaction rates
• Repeat courses effective for many patients
• Similar efficacy to other high molecular weight HA products

Comparison to Other Brands

Side Effects and Safety

Common Side Effects (5-10% of patients)

• Injection site pain - Usually mild, resolves in 24-48 hours
• Knee swelling - Temporary fluid accumulation
• Stiffness - Often improves after 48 hours
• Warmth at injection site - Normal inflammatory response

Rare But Serious (Less than 1%)

• Infection (septic arthritis) - Requires immediate medical attention
• Severe allergic reaction - Rash, difficulty breathing (call 911)
• Acute inflammatory reaction - Severe swelling, heat, redness (pseudoseptic reaction)

Managing Side Effects

After each injection:

• Ice the knee 15-20 minutes every 2 hours for first day
• Avoid strenuous activity for 48 hours (no running, heavy lifting)
• Take acetaminophen if needed (avoid NSAIDs for 48 hours)
• Elevate leg when resting
• Call your provider if pain worsens after 48 hours

Bird Allergy Safety: Why It Matters

Many viscosupplementation products (Synvisc, Supartz, Orthovisc) are derived from rooster combs—chicken tissue rich in hyaluronic acid. This creates risk for patients with:

• Egg allergies
• Poultry allergies
• Bird feather allergies
• History of anaphylaxis to avian proteins

How Hymovis Is Different

Hymovis uses biofermented hyaluronic acid—produced by bacterial cultures (specifically Bacillus subtilis) in controlled laboratory conditions. No animal tissue involved.

This means:

• No avian proteins that trigger allergic reactions
• No risk of cross-contamination with egg or poultry allergens
• Suitable for patients with religious dietary restrictions (kosher, halal concerns)
• Potentially lower allergic reaction risk overall

Important: While Hymovis avoids avian proteins, you should still inform your provider about all allergies. Reactions to HA itself (though rare) can still occur.

Insurance Coverage and Cost

Medicare Coverage

Medicare Part B covers Hymovis when:

• You have documented knee osteoarthritis (ICD-10 code)
• Conservative treatments failed (6+ weeks of PT, oral medications)
• Provider documents medical necessity
• Administered in approved setting (office, ASC, hospital outpatient)

Typical Medicare cost:

• 20% coinsurance after Part B deductible ($240 in 2025)
• Per-course out-of-pocket: $120-$200 (both injections)

Private Insurance

Coverage varies widely:

• Covered plans: $50-$150 per injection copay
• Prior authorization: Often required (plan ahead 2-4 weeks)
• Step therapy: May require trying cortisone first
• Not covered: $600-$900 full cost per course

Denial common reasons:

• Insufficient conservative treatment documentation
• “Experimental” designation (rare, but some plans lag FDA approval)
• Not meeting severity criteria (mild OA)

Cost Comparison (Without Insurance)

Financial Assistance

• Fidia Pharma patient assistance: Ask your provider’s office
• GoodRx/RxSaver: May offer discounts (less common for injections)
• Provider payment plans: Many practices offer installment options

Hymovis vs. Alternatives: Positioning Guide

When to Choose Hymovis Over Single-Shot Brands

Choose Hymovis if:

• You prefer gradual improvement over immediate effect
• You want higher total HA volume (4mL vs 6mL Synvisc-One)
• You have bird allergies (Synvisc-One is avian-derived)
• Your insurance covers both similarly

Choose Synvisc-One if:

• You want absolute fewest appointments (1 visit)
• You prefer cross-linked gel for longer residence time
• Your provider has more experience with it
• No allergy concerns

When to Choose Hymovis Over 3-Shot Brands

Choose Hymovis if:

• You want fewer appointments (2 vs 3 visits)
• You prefer HYADD4 technology over linear HA
• You have bird allergies (Euflexxa, Supartz are non-avian but variable)
• Cost is similar

Choose Euflexxa/Supartz if:

• You want the most gradual onset possible
• Your insurance prefers these brands
• Your provider recommends weekly build-up
• You want lowest per-injection cost (Supartz)

The Unique Middle Ground

Hymovis occupies a strategic position:

*Euflexxa is biofermented; Supartz is avian-derived

Frequently Asked Questions

How long does each Hymovis injection take?

The actual injection takes 5-10 minutes. With check-in, preparation, and post-injection observation, expect 15-30 minutes per visit.

Do I need both injections?

Yes. The 2-injection protocol is FDA-approved as a course. Receiving only one injection provides incomplete dosing and may reduce effectiveness.

Can I delay the second injection beyond 1 week?

The approved protocol is 1 week apart. If you must reschedule, talk to your provider—most will allow 7-10 days, but longer delays may require restarting the course.

Will I feel better after the first injection?

Some patients report mild improvement after injection 1, but most notice significant relief 4-6 weeks after completing both injections. Be patient—HA takes time to work.

How soon can I repeat Hymovis if it wears off?

Most providers recommend waiting at least 6 months between courses. Medicare typically covers repeat courses every 6-12 months if medically necessary.

Is Hymovis painful to receive?

Pain tolerance varies, but most patients describe:

• During injection: Pressure, mild burning (5-15 seconds)
• After injection: Achiness similar to a flu shot (24-48 hours)
• Numbing: Local anesthetic can be used to reduce discomfort

Using fluoroscopic guidance (real-time X-ray) ensures accurate placement, which can reduce post-injection pain.

Can I get Hymovis in both knees?

Yes. If both knees have osteoarthritis, you can receive injections bilaterally. Some providers do both knees same day; others alternate weeks to monitor response.

Does Hymovis work for hips, shoulders, or ankles?

No. Hymovis is FDA-approved only for knee osteoarthritis. Off-label use in other joints is not recommended or covered by insurance.

Will Hymovis cure my arthritis?

No. Hymovis manages symptoms (pain, stiffness) but doesn’t reverse cartilage damage or cure osteoarthritis. It’s a tool to maintain function and delay surgery, not a permanent fix.

What if Hymovis doesn’t work for me?

If you don’t respond after 8-12 weeks:

• Try alternative HA brand (different molecular weight may help)
• Consider PRP injections (platelet-rich plasma)
• Reassess for surgery if quality of life is severely impacted
• Optimize other treatments (physical therapy, weight management, bracing)

Is Hymovis better than cortisone shots?

Different purposes:

• Cortisone: Fast relief (24-48 hours), short duration (4-8 weeks), anti-inflammatory
• Hymovis: Slower onset (4-6 weeks), longer duration (6-12 months), joint lubrication

For acute flares, cortisone is better. For long-term management, Hymovis is superior. Some patients get cortisone first, then Hymovis 2 weeks later.

Can I exercise after Hymovis injections?

• Avoid for 48 hours: Running, jumping, heavy lifting, squatting
• Safe immediately: Walking, light stretching, daily activities
• Resume fully: After 48-72 hours if no swelling

Will insurance cover Hymovis if I’m under 50?

Age isn’t typically a factor—osteoarthritis diagnosis is. If you have documented OA (confirmed by X-ray or MRI) and failed conservative treatment, insurance may cover regardless of age.

How do I find a provider who offers Hymovis?

Ask your orthopedic doctor or rheumatologist. Not all practices stock every brand. If your provider doesn’t offer Hymovis but you’re interested due to allergies, request a referral to one who does.

Medical Disclaimer

This guide is for educational purposes only and does not replace professional medical advice. Hymovis is a prescription medical device that must be administered by a licensed healthcare provider. Treatment decisions should be made in consultation with your doctor based on your specific condition, medical history, and individual risk factors.

Always inform your provider about:

• All allergies (food, medication, environmental)
• Current medications and supplements
• Previous joint injections and responses
• Medical conditions (diabetes, bleeding disorders, infections)
• Pregnancy or breastfeeding status

If you experience severe pain, fever, or signs of infection after injection, seek medical attention immediately.

Last medically reviewed: January 2025

Sources: FDA prescribing information, peer-reviewed studies in Journal of Orthopaedic Surgery and Research (2016), Cartilage (2016), Medicare coverage guidelines, manufacturer clinical data.