When your doctor recommends HA (hyaluronic acid) injections for your knee arthritis, one of the first questions is: single injection or a series? Here’s what you need to know to understand the difference.
The Basic Difference
Single-injection products deliver the full treatment in one appointment:
- One visit to the doctor
- One injection
- Done
Series products spread the treatment across multiple appointments:
- 3 to 5 weekly visits
- One injection per visit
- Treatment completed over several weeks
Why Are There Two Approaches?
The difference comes down to how the products are made:
Single-injection products (like Synvisc-One, Monovisc, Durolane) contain:
- A larger volume of gel in one dose
- Often a higher molecular weight formula
- Designed to provide lasting effect from one treatment
Series products (like Euflexxa, Supartz, Hyalgan) contain:
- Smaller doses given over time
- Sometimes different formulations
- Built up gradually in the joint
Both approaches aim to achieve the same result - reducing pain and improving joint function.
Comparing Effectiveness
Here’s what research tells us:
| Factor | Single Injection | Series (3-5 shots) |
|---|---|---|
| Pain relief | Similar | Similar |
| Duration of benefit | 6-12 months | 6-12 months |
| Time to feel improvement | 2-4 weeks | 2-4 weeks |
| Studies supporting use | Multiple | Multiple |
Most head-to-head studies show comparable effectiveness between the two approaches. Neither is clearly “better” for pain relief.
Practical Differences That Matter
Convenience
Single injection wins if:
- You have a busy schedule
- You travel frequently
- You prefer fewer medical appointments
- Your doctor’s office is far away
Series might work if:
- You prefer a gradual approach
- You want to spread out any potential side effects
- Your schedule allows weekly visits
Cost Considerations
The total treatment cost is often similar, but how you pay may differ:
- Single injection: One larger payment or copay
- Series: Multiple smaller payments spread over weeks
Some people prefer series because:
- Copays feel more manageable when spread out
- If you have a reaction, you haven’t received the full treatment
- Insurance approval might be easier for some series products
Insurance Coverage
Both types are generally covered by Medicare and most private insurance for knee osteoarthritis. However:
- Some plans prefer specific brands
- Prior authorization requirements vary
- Copay amounts differ by product
Check with your insurance before the procedure.
Which Should You Choose?
Consider a single injection if:
- You want to minimize doctor visits
- You’ve had successful single-injection treatment before
- Your schedule is unpredictable
- You prefer “one and done”
Consider a series if:
- You want to spread out the cost
- You’re trying HA injections for the first time and want to see how you respond
- Your doctor has more experience with series products
- Your insurance strongly prefers a specific series product
Your Doctor’s Recommendation
Ultimately, your doctor will help guide this decision based on:
- Their experience with different products
- Your specific joint condition
- Insurance and cost factors
- Your personal preferences and schedule
Both approaches can provide excellent results. The “best” choice is the one that fits your situation and that your doctor is comfortable administering.
The Bottom Line
Single and series HA injections are different routes to the same destination. Don’t stress too much about which one is “better” - focus on finding a product and approach that works for your life and your healthcare coverage.