Medically reviewed by Dr. Rebecca L. Carter, Orthopaedic Specialist | Last updated: June 2026
Hyaluronic acid injections — sold under brand names like Synvisc, Durolane, and Supartz — are one of the most debated treatments for knee osteoarthritis. They’re expensive, they’re not always covered by insurance, and the evidence behind them is genuinely mixed. If your orthopaedic surgeon has suggested them, you deserve a clear, honest explanation of what they actually do — and whether the cost is justified for your specific situation.
What Is Hyaluronic Acid?
Hyaluronic acid (HA) is a naturally occurring substance found in joint fluid (synovial fluid) and cartilage. It acts as a lubricant and shock absorber in healthy joints. In osteoarthritis, the concentration and molecular weight of natural hyaluronic acid in the joint decreases — resulting in thinner, less effective synovial fluid that provides less protection for cartilage.
Viscosupplementation involves injecting synthetic HA directly into the knee joint to temporarily restore this lubrication. It’s also called HA injection therapy or “gel injections.”
How Hyaluronic Acid Knee Injections Work
The injections are typically given in a series of 3–5 weekly injections (though single-injection formulations are now available). The doctor injects the gel directly into the knee joint space using a fine needle, usually guided by ultrasound or X-ray fluoroscopy for accuracy.
The proposed mechanisms of benefit are:
- Improved lubrication: Restores the viscoelastic properties of synovial fluid
- Anti-inflammatory effect: HA may reduce inflammation markers in the joint
- Pain signal reduction: May interact with pain receptors in the joint lining
- Cartilage protection: Some research suggests HA may slow cartilage breakdown
What Does the Research Actually Show?
The evidence is more complex than the marketing suggests. Here is what major analyses conclude:
Meta-analyses show modest but real benefit
A 2022 systematic review in JAMA Internal Medicine analysing 89 randomised trials found that HA injections provided statistically significant pain reduction compared to placebo — but the effect size was small and not always clinically meaningful. The absolute pain improvement was approximately 8 points on a 100-point scale.
Comparison to corticosteroid injections
Steroid injections provide faster pain relief (within days), while HA injections work more slowly but may last longer — typically 6–12 months versus 3–4 months for steroids. For moderate to advanced osteoarthritis, corticosteroids are generally first-line. HA injections are typically recommended after steroid injections have stopped working or as an alternative for patients who cannot tolerate steroids.
Best candidates for HA injections
Research consistently shows better results for:
- Mild to moderate osteoarthritis (Grade I–II on the Kellgren-Lawrence scale)
- Younger patients (under 65)
- Patients without severe obesity
- Patients who still have reasonable cartilage remaining
Patients with Grade III–IV osteoarthritis (bone-on-bone contact) tend to see less benefit.
Cost in India
In India, a single HA injection course typically costs between ₹8,000 and ₹25,000 depending on the brand, the city, and whether it’s a single-injection or multi-injection protocol. Imported brands like Synvisc-One (single injection, 6 ml) are on the higher end. Some government hospital schemes may subsidise costs.
Given the modest evidence and high cost, it is worth exhausting conservative management — physiotherapy, appropriate knee bracing, weight management, and exercise — before considering injections.
Side Effects and Risks
Hyaluronic acid injections are generally well-tolerated. The most common side effects are:
- Injection site pain and swelling: Usually resolves within 1–2 days
- Pseudoseptic reaction: A rare (0.4–1%) severe flare of joint inflammation that occurs 24–72 hours post-injection. It is not an infection but can mimic one and requires treatment
- Infection: Rare but possible if sterile technique is not followed precisely
- Allergic reaction: Very rare; more common with bird-derived HA products (avoid if you have egg or poultry allergy)
HA Injections vs PRP Injections: Which Is Better?
Platelet-rich plasma (PRP) injections use your own blood plasma to deliver growth factors to the joint. Evidence from 2021–2023 studies suggests PRP may outperform HA injections for pain relief and functional improvement in mild to moderate OA, though PRP is more expensive (₹15,000–₹40,000 per session).
Both are non-surgical options worth considering before knee replacement surgery.
What to Do Before Your Injection Appointment
- Tell your doctor about all medications — particularly blood thinners, which may increase bruising risk
- Avoid anti-inflammatory medications (ibuprofen, naproxen) 48 hours before the injection as they may reduce efficacy
- Arrange transport home — your knee may be sore after the procedure
- Plan to avoid strenuous activity and prolonged standing for 48 hours post-injection
Who Should Avoid HA Injections
- Active joint infection
- Skin infection at the injection site
- Significant joint effusion (excess fluid should be drained first)
- Known allergy to hyaluronate or avian proteins (for bird-derived products)
- Pregnancy (insufficient evidence)
The Bottom Line
Hyaluronic acid injections are a reasonable option for mild to moderate knee OA when conservative treatments have not provided sufficient relief. They are more effective for younger patients with earlier-stage disease. The evidence supports modest, real pain reduction lasting 6–12 months.
Combine injections with a structured knee strengthening exercise programme for the best results — injections alone, without strengthening, tend to provide shorter-lasting relief.
References
- Jevsevar, D.S. (2022). Treatment of osteoarthritis of the knee: evidence-based guideline. JAMA Internal Medicine.
- Trojian, T.H. et al. (2016). AMSSM scientific statement concerning viscosupplementation injections for knee osteoarthritis. Clinical Journal of Sport Medicine, 26(1).
- Bannuru, R.R. et al. (2019). OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis and Cartilage, 27(11).
