Quick Answer
Yes, Medicare Part B covers Zilretta injections for knee osteoarthritis. Zilretta is an extended-release triamcinolone acetonide injection — a corticosteroid, not a hyaluronic acid product. It is the only FDA-approved extended-release corticosteroid for knee OA. Most patients pay 20% coinsurance after meeting their Part B deductible, though out-of-pocket costs are higher than standard cortisone due to Zilretta’s premium pricing.
Medicare Part B Coverage for Zilretta
Zilretta is manufactured by Pacira BioSciences. Unlike standard cortisone injections that release medication all at once, Zilretta uses microsphere technology to deliver triamcinolone acetonide gradually over time. This extended-release design is intended to provide longer-lasting pain relief while reducing the blood sugar spikes commonly seen with standard corticosteroid injections.
Medicare covers Zilretta under Part B (the medical benefit) because it is administered in a physician’s office or outpatient setting.
Key coverage facts:
- Covered under Part B as a physician-administered injectable
- No prior authorization generally required under Original Medicare
- Subject to Local Coverage Determinations (LCDs) from your regional MAC
- Must meet medical necessity criteria documented in your medical records
- Higher cost than standard cortisone — expect higher coinsurance amounts
- FDA-approved only for knee OA — not covered for other joints
Coverage Requirements
Medical Necessity Criteria
For Medicare to pay for Zilretta, your medical records must show:
- Diagnosis of knee osteoarthritis with ICD-10 code M17.x
- Medical necessity documentation explaining why Zilretta is appropriate (this is particularly important given its higher cost compared to standard cortisone)
- Treatment administered in the knee — Zilretta is only FDA-approved for knee osteoarthritis
- Provider enrolled in Medicare
Unlike HA injections, Medicare does not typically require documentation of prolonged conservative treatment failure before covering corticosteroid injections. However, given Zilretta’s cost, thorough documentation strengthens your claim.
Billing Codes
| Code | Description | 2026 Estimated Allowable |
|---|---|---|
| J3304 | Zilretta (triamcinolone acetonide ER), per 1 mg | Approximately $500 - $600 total (32 mg dose) |
| 20610 | Arthrocentesis, large joint (knee) | $85 - $110 |
| 77002 | Fluoroscopic guidance (if used) | $75 - $95 |
Your provider bills Medicare using J-code J3304 for Zilretta. The standard dose is 32 mg, and the J-code is billed per milligram, so the total claim reflects the full 32 mg dose.
Frequency Limits
- One Zilretta injection per knee is the recommended approach
- Like all corticosteroid injections, clinical guidelines suggest no more than 3-4 injections per joint per year
- The extended-release design means each injection is intended to last longer than standard cortisone
- Your provider should document the clinical response and spacing between injections
Your Out-of-Pocket Costs
| Item | Amount |
|---|---|
| Part B deductible (2026) | $257/year |
| Coinsurance | 20% of Medicare-approved amount |
| Typical total patient cost | $100 - $150 per injection |
| With Medigap | May cover the 20% coinsurance |
Cost Comparison: Zilretta vs. Standard Cortisone
| Factor | Zilretta | Standard Cortisone |
|---|---|---|
| Medicare-approved amount | $500 - $600 | $10 - $30 |
| Your 20% coinsurance | $100 - $120 | $2 - $6 |
| Injection procedure fee | Same | Same |
| Total out-of-pocket | Higher | Lower |
| Duration of relief | Potentially longer | Shorter (6-12 weeks typical) |
Zilretta costs significantly more than standard cortisone. The trade-off is potentially longer-lasting relief and less impact on blood sugar levels — an important consideration for patients with diabetes.
Medicare Advantage Plans
If you have a Medicare Advantage (Part C) plan:
- Coverage generally follows Original Medicare guidelines
- Prior authorization is more likely for Zilretta than standard cortisone, given its higher cost
- Some plans may prefer standard cortisone as a first-line treatment before approving Zilretta
- Step therapy requirements may apply — your plan might require you to try standard cortisone first
- Contact your plan’s member services to verify coverage and any special requirements
What If Medicare Denies Coverage?
If your Zilretta claim is denied:
- Request the denial reason in writing
- Gather supporting documents including your OA diagnosis, treatment records, and a letter from your provider explaining why Zilretta (rather than standard cortisone) is medically necessary
- File a redetermination (Level 1 appeal) within 120 days
- Emphasize specific clinical reasons for choosing Zilretta — for example, if you have diabetes and need to minimize blood sugar spikes, or if standard cortisone provided only brief relief
Zilretta Product Details
| Feature | Detail |
|---|---|
| Manufacturer | Pacira BioSciences |
| Active ingredient | Triamcinolone acetonide (extended-release) |
| Drug class | Corticosteroid (NOT hyaluronic acid) |
| Injection schedule | 1 injection per treatment |
| FDA-approved for | Knee osteoarthritis only |
| Dose | 32 mg per injection |
| Technology | Microsphere extended-release delivery |
| Duration of effect | Studies show pain relief up to 12 weeks |
Zilretta is fundamentally different from hyaluronic acid viscosupplements. While HA products aim to lubricate and cushion the joint, Zilretta is a corticosteroid that reduces inflammation. Its microsphere technology releases the medication gradually rather than all at once, which may result in longer-lasting anti-inflammatory effects and fewer systemic side effects like blood sugar elevation.
Important Considerations
Blood Sugar Impact
Standard corticosteroid injections can cause significant blood sugar spikes in patients with diabetes. Zilretta’s extended-release formulation was designed to minimize this effect. Clinical studies showed that Zilretta caused less blood glucose elevation compared to standard triamcinolone acetonide. If you have diabetes, discuss this benefit with your provider.
Cartilage Concerns
Like all corticosteroid injections, repeated use may affect cartilage health over time. A 2019 JAMA study found that repeated standard cortisone injections were associated with greater cartilage volume loss. Discuss the frequency of treatment with your doctor and consider whether hyaluronic acid injections might be a better long-term option.
Frequently Asked Questions
How often will Medicare pay for Zilretta?
Medicare covers Zilretta as needed for knee OA, but clinical guidelines recommend no more than 3 to 4 corticosteroid injections per joint per year. Your provider determines the appropriate frequency based on your response to treatment.
Do I need prior authorization for Zilretta under Medicare?
Original Medicare generally does not require prior authorization for Zilretta. However, Medicare Advantage plans frequently require prior authorization for Zilretta given its higher cost compared to standard cortisone. Check with your plan.
Is Zilretta the same as a cortisone shot?
Zilretta contains the same type of corticosteroid (triamcinolone) as some standard cortisone injections, but it uses extended-release microsphere technology. This means the medication is released slowly over time rather than all at once. The result may be longer-lasting relief and less impact on blood sugar.
Can Zilretta be used in joints other than the knee?
No. Zilretta is only FDA-approved for osteoarthritis of the knee. Using it in other joints would be considered off-label, and Medicare may not cover off-label use. Standard cortisone injections are available for other joints.
Is Zilretta better than standard cortisone?
Zilretta may offer advantages for some patients, particularly those with diabetes (less blood sugar impact) or those who want potentially longer-lasting relief. However, it costs significantly more. For many patients, standard cortisone provides adequate relief at a much lower cost. Discuss the pros and cons with your provider.