If you and your doctor have decided that sacral neuromodulation (SNM) is the right treatment for your overactive bladder or urinary incontinence, the next question is: which device? Two FDA-approved systems are available — Axonics and Medtronic InterStim. While both use the same underlying principle of stimulating the sacral nerves to restore bladder control, there are significant differences in technology, clinical evidence, and long-term value that are worth understanding before you make your decision.
At Bladder Centers of America in Phoenix, AZ, we offer both systems but have found that the Axonics platform consistently delivers superior outcomes for our patients. In this guide, we’ll break down the key differences — including the clinical data — so you can have an informed conversation with Dr. McJunkin about which option is best for you.
Why We Prefer Axonics at Bladder Centers of America
While both devices are FDA-approved and clinically effective, our experience — and the published clinical evidence — gives us strong confidence in the Axonics platform. Here’s why:
- Stronger clinical trial data: The ARTISAN-SNM study demonstrated a 93% responder rate at 2 years with 94% patient satisfaction — the most rigorous prospective evidence available for any SNM device
- Modern device engineering: Axonics offers two purpose-built options — a tiny 5cc rechargeable (R20) and a 10cc recharge-free (F15) — both smaller, more advanced, and longer-lasting than competing devices
- Fewer lifetime procedures: With the R20’s 20+ year rechargeable battery or the F15’s 15–20+ year recharge-free battery, most patients will never need a replacement surgery
- Superior MRI compatibility: Full-body 1.5T and 3T MRI labeling with a pocket-sized remote that confirms MRI readiness without an office visit
- Constant current stimulation: Axonics automatically adjusts stimulation output to maintain consistent therapy even as tissue impedance changes over time
The Clinical Evidence: ARTISAN-SNM Study
The strongest evidence supporting Axonics sacral neuromodulation comes from the ARTISAN-SNM study — a prospective, multicenter pivotal trial that followed 129 patients across 19 centers in the United States and Europe. The results, published in Neurourology and Urodynamics, are among the most compelling in the SNM field:
ARTISAN-SNM: Key Outcomes at 2 Years
- 93% responder rate — 121 of 129 implanted patients achieved a 50% or greater reduction in urinary urgency incontinence (UUI) episodes at 2 years
- 75% average reduction in UUI episodes across all study participants
- Daily UUI episodes dropped from 5.6 at baseline to just 1.0 at 2 years
- Large leaks nearly eliminated — among the 76 patients tracking large leaks, episodes dropped from 1.6/day to 0.1/day
- Urinary frequency improved significantly — 80% of participants had more than 8 voids per day at baseline (average 11.6/day), reduced to 8.6/day at 2 years
- 94% patient satisfaction — and 93% said they would undergo the therapy again with the same expected results
- Less than 2% reported implant site pain
The RELAX-OAB study — a separate European trial of 51 patients — showed similar results: 90% of responders maintained therapeutic benefit at 2 years, with a 29-point improvement in quality of life (more than 3 times the threshold for clinical significance) and zero serious device-related adverse events.
How Does InterStim’s Clinical Data Compare?
Medtronic’s primary clinical evidence comes from the InSite study, which compared InterStim to standard medical therapy (OAB medications). While this was a randomized controlled trial — which is valuable — there are important differences in how the data reads:
- At 6 months, 76% of InterStim patients achieved therapeutic success vs. 49% on medications
- At 5 years, the success rate was 82% using completers analysis (only counting patients who stayed in the study) or 67% using the more conservative modified completers analysis
- The most common adverse events included undesirable stimulation changes (22%), implant site pain (15%), and therapy becoming ineffective (13%)
Notably, no head-to-head randomized trial has directly compared InterStim to Axonics. However, when we look at the published data side by side, the Axonics ARTISAN study’s 93% responder rate at 2 years is substantially higher than the 67–82% range reported in the InterStim InSite study at 5 years, with a notably lower adverse event profile.
Two Axonics Options: R20 (Rechargeable) and F15 (Recharge-Free)
One of the advantages of the Axonics platform is that it offers two distinct device options to match different patient preferences — both built on the same proven technology:
Axonics R20 — Our Preferred Choice
The Axonics R20 is a fourth-generation rechargeable neurostimulator and is the device Dr. McJunkin most often recommends:
- Volume: Only 5cc — one of the smallest neurostimulators ever made, roughly the size of a small USB drive
- Battery life: 20+ years — designed to potentially last a lifetime without replacement surgery
- Recharging: Once every 6–10 months on average, for about 1 hour using a wireless belt worn over the implant site. This is a dramatic improvement over earlier rechargeable devices that required monthly charging
- Full-body MRI compatible (1.5T and 3T) — with a pocket-sized remote that confirms MRI readiness at home
- Constant current stimulation that automatically adjusts to maintain consistent therapy
- One universal tined lead compatible with both R20 and F15, giving flexibility if preferences change
At only 5cc and with recharging needed just once or twice a year, the R20 offers the best combination of miniature size, extreme longevity, and minimal maintenance of any SNM device available today.
Axonics F15 — Recharge-Free Option
For patients who prefer a completely maintenance-free experience, the Axonics F15 offers:
- Volume: 10cc — still 20% smaller than the Medtronic InterStim
- Battery life: 15–20+ years (17.6 years at typical 1 mA settings, over 20 years at lower settings) — no recharging ever required
- Zero maintenance — true “set it and forget it” therapy
- Full-body MRI compatible (1.5T and 3T)
- Same tined lead as the R20, same constant current platform
- Recharge-free remote control with SmartMRI technology
Where Does InterStim Fit In?
Medtronic pioneered sacral neuromodulation in 1997 and deserves credit for establishing the therapy. The InterStim X is their current-generation device. However, the technology has not kept pace with Axonics’ innovations:
- Non-rechargeable only — no rechargeable option, meaning a replacement surgery is inevitable when the battery depletes
- Larger device than both Axonics options
- Battery life up to 15 years — competitive with the Axonics F15, but with a larger form factor
- Longest clinical track record — InterStim has been available since 1997, giving it the most years of real-world use data
- Less robust prospective clinical evidence — the InSite study’s modified completers analysis showed 67% success at 5 years, notably lower than Axonics’ 93% at 2 years
InterStim remains a valid option, particularly for patients who have specific reasons to choose it. But for most patients we see at Bladder Centers of America, the Axonics platform offers clear advantages in device size, battery longevity, clinical evidence, and patient satisfaction.
Side-by-Side Comparison
| Feature | Axonics R20 (Rechargeable) | Axonics F15 (Recharge-Free) | InterStim X |
|---|---|---|---|
| Device Volume | 5cc | 10cc | Larger than F15 |
| Battery Life | 20+ years | 15–20+ years | Up to 15 years |
| Recharging | ~1 hr every 6–10 months | None | None |
| Replacement Surgery | Potentially never | After 15–20+ years | After ~15 years |
| Stimulation Type | Constant current (auto-adjusting) | Constant current (auto-adjusting) | Voltage-driven |
| MRI Compatible | Full body 1.5T and 3T | Full body 1.5T and 3T | Full body 1.5T and 3T |
| Key Clinical Trial | ARTISAN-SNM: 93% responders at 2 years | InSite: 67–82% at 5 years | |
| Patient Satisfaction | 94% satisfied (ARTISAN) | Not prominently reported | |
| Adverse Events | <2% implant site pain | 15% implant site pain | |
Frequently Asked Questions
Why hasn’t there been a head-to-head study?
Conducting a randomized head-to-head trial comparing two implantable devices is extremely expensive and logistically challenging — patients would need to consent to receiving whichever device they’re randomized to, and long-term follow-up would take years. While such a study would be ideal, the existing individual trial data gives us meaningful insight into how each device performs. The ARTISAN study’s prospective design with 129 patients across 19 centers provides strong evidence for Axonics’ effectiveness.
What does recharging the Axonics R20 actually involve?
Recharging is simple and painless. You wear a lightweight wireless belt around your waist for about one hour. The belt wirelessly charges the implant through your skin. With the R20’s advanced battery technology, most patients only need to do this once every 6 to 10 months — a massive improvement over earlier rechargeable devices. In the ARTISAN study, 91% of patients found recharging easy and 94% rated the frequency and duration as acceptable.
Is the Axonics R20 really only 5cc?
Yes. The R20 is one of the smallest neurostimulators ever made. To put it in perspective, 5cc is roughly the size of a large almond. It’s implanted in the upper buttock area and is virtually undetectable under clothing. The small size also means less tissue disruption during implantation and greater patient comfort.
Does insurance cover Axonics?
Yes. Both Axonics (R20 and F15) and InterStim are covered by Medicare and most major insurance plans for their FDA-approved indications — overactive bladder, urinary retention, and fecal incontinence. Coverage is typically the same regardless of which device you choose. Our team at Bladder Centers of America will verify your specific benefits before your procedure.
Can I switch devices later?
Both Axonics devices (R20 and F15) use the same universal tined lead, which means if your clinical needs or preferences change, your doctor can replace just the neurostimulator without touching the lead — for example, switching from an R20 to an F15 or vice versa. This lead compatibility is unique to the Axonics platform and provides built-in flexibility that InterStim cannot match.
How to Decide: Our Recommendation
For most patients at Bladder Centers of America, we recommend the Axonics R20. Here’s why:
- At only 5cc, it’s the smallest and most comfortable option available
- The 20+ year rechargeable battery means most patients will never need a replacement surgery
- Recharging once every 6–10 months is virtually no maintenance at all
- The ARTISAN study’s 93% response rate and 94% satisfaction rate give us the highest confidence in outcomes
- Constant current stimulation provides more consistent therapy than voltage-driven alternatives
For patients who strongly prefer zero maintenance, the Axonics F15 is an excellent alternative — still smaller and longer-lasting than the InterStim X, with the same proven clinical platform.
Dr. McJunkin will discuss all options with you during your consultation and help you choose the device that best fits your lifestyle, medical history, and personal preferences.
Ready to Take the Next Step?
If you’re living with overactive bladder, urinary incontinence, or fecal incontinence that hasn’t responded to medications, sacral neuromodulation with the Axonics system can help you regain control of your life. Our patients consistently tell us it was the best decision they ever made.
Schedule your consultation today. Call Bladder Centers of America at (480) 757-8777 or request an appointment online. We’ll evaluate your candidacy, walk you through the trial process, and answer every question you have.
Related reading: Sacral Neuromodulation for Bladder Control: Everything You Need to Know