Medial Branch Blocks (MBB) & Radiofrequency Ablation (RFA)
What Is Facet Joint Pain?
Your spine is made up of bones called vertebrae stacked on top of each other. In the back of your spine, there are small joints called facet joints. These joints help your back bend, twist, and stay stable. Like any joint in your body — your knee, your hip, your shoulder — they can become painful over time from arthritis, injury, or everyday wear and tear.
When facet joints are irritated, the pain tends to feel dull and achy, and it often spreads into the shoulders, buttocks, or thighs. Unlike disc-related pain, it usually does not shoot below the knee. You may also notice stiffness that is worse in the morning or after sitting for a long time, pain that gets worse when you lean backward or twist, and tenderness along the sides of the spine.
If this sounds familiar, and other treatments have not given you lasting relief, you may be a candidate for the two-step approach described below.
The Nerves That Carry the Pain
Each facet joint is supplied by small nerves called medial branch nerves. Think of them like electrical wires — they carry the pain signal from the joint to your brain. No signal, no pain.
There are two steps to addressing this pain source. Step 1 is a medial branch block, which is a diagnostic injection used to confirm that these nerves are actually the source of your pain. Step 2 is radiofrequency ablation, a procedure that uses heat to disrupt the nerve signal and provide lasting relief.
You always start with Step 1. Radiofrequency ablation is only performed after the diagnostic block confirms that these nerves are the right target. However, if you have previously received a successful Radiofrequency ablation in the past at a particular nerve level, you do not need to re-do the medial branch blocks.
Step 1: The Medial Branch Block
What is it?
A medial branch block is a simple injection of local anesthetic — numbing medicine — placed next to the small nerves that supply your painful facet joints. Its primary purpose is diagnostic: we want to know if blocking these nerves takes your pain away. If it does, we have confirmed the source of your pain and you are a strong candidate for radiofrequency ablation.
What happens during the procedure?
You will lie on a procedure table, and the skin over the injection area will be cleaned and numbed. Using live X-ray (fluoroscopy) or ultrasound guidance, your doctor places a small needle next to each target nerve and injects a small amount of numbing medicine. The whole procedure usually takes 15 to 30 minutes. Most patients feel only mild pressure or brief stinging, and sedation is generally not needed.
After the injection — what to watch for
The most important thing you can do after a medial branch block is track your pain level for the rest of the day. Write it down if you can. If your pain improves by 50% or more within the first few hours, the test is positive — those nerves are causing your pain. The numbing medicine wears off after a few hours and your original pain may return. That is expected and does not mean something went wrong. You can return to normal, light activity the same day and should avoid strenuous exercise for 24 hours.
Why do I need two injections?
Insurance guidelines and medical best practices often require two positive medial branch blocks before approving radiofrequency ablation. This extra step helps confirm you are a true responder — not someone who just had a good day — and increases the likelihood that the ablation will work well for you. Your doctor will let you know how many diagnostic blocks are needed in your case.
Step 2: Radiofrequency Ablation
What is it?
Radiofrequency ablation — also called RFA or rhizotomy — uses heat generated by radio waves to disrupt the medial branch nerve. When the nerve is disrupted, it can no longer send the pain signal from the facet joint to your brain. This is not surgery. There are no cuts, no stitches, and no hospital stay.
Who is a good candidate?
You are likely a good candidate if you had significant pain relief (50% or more) after your medial branch block(s), your pain has lasted longer than 3 months, other treatments such as physical therapy, medications, or chiropractic care have not given lasting relief, and imaging such as X-ray or MRI supports facet joint arthritis as a contributing cause.
What happens during the procedure?
You will be positioned on a procedure table and connected to monitoring equipment. The skin is numbed with local anesthetic. Using fluoroscopy for precise guidance, your doctor places a special RFA needle next to each target nerve. Motor testing is done first — you may feel buzzing or mild pressure, which is normal and confirms the needle is in the right place. Local anesthetic is then injected, and heat is applied for about 90 seconds per nerve. You should not feel significant pain during this step. The full procedure typically takes about 20 minutes depending on how many nerves are treated.
Before your procedure, make sure to tell your doctor about all medications you take — especially blood thinners — and any allergies to local anesthetics. If sedation is planned, arrange a driver to take you home.
After RFA: What to Expect
The first few days
You may feel sore at the injection sites for a few days, which is completely normal. Some patients also notice a temporary increase in pain for one to two weeks while the nerve settles. This does not mean the procedure failed — it is a normal part of the healing process. Ice packs applied for 15 to 20 minutes at a time can help with soreness. Avoid applying heat to the area for the first 48 hours. You can resume light daily activities the same day and should avoid strenuous exercise for the next day or two.
When will I feel better?
Pain relief after RFA is gradual, not immediate. Most patients begin to notice improvement within 2 to 6 weeks. Full benefit may take up to 3 months. Here is a general timeline of what to expect:
1–2 weeks: Soreness resolves; some patients notice early improvement
2–6 weeks: Most patients experience meaningful pain relief
6–12 weeks: Maximum benefit is typically reached
1–2+ years: Average duration of relief, which varies by individual
How long does relief last?
RFA provides long-lasting but temporary relief for most people. Nerves can slowly regrow over time, and on average relief lasts 1 to 2 years, though some patients have longer benefit. If your pain returns, the procedure can often be repeated with similar results.
RFA works best as part of a complete treatment plan
Think of RFA as a tool that reduces pain enough to let you do the work that leads to lasting improvement. Exercise, physical therapy, and movement are essential for long-term spine health. Your doctor may recommend continuing physical therapy or a home exercise program alongside RFA to get the most out of your results.
Risks and Complications
Both medial branch blocks and radiofrequency ablation are very safe procedures, and serious complications are rare. The most common side effects are temporary soreness or bruising at the injection site, which typically resolve within a few days. Other possible risks include temporary numbness or weakness (usually resolving within days to weeks), infection (rare, as sterile technique is used throughout), bleeding (rare when blood thinners are stopped beforehand as instructed), and incomplete or no relief in some patients.
Your doctor will review your specific risks with you before the procedure based on your health history and medications.
Questions to Ask Your Doctor
Coming to your appointment prepared is always a good idea. Here are some questions worth asking:
Which levels of my spine will be treated?
How many nerves will be targeted?
Do I need to stop any medications before the procedure, and for how long?
Will I need sedation, and should I arrange a driver?
How will I know if the procedure worked?
What should I do if my pain does not improve after 6 to 8 weeks?
How soon can I return to exercise and physical therapy?
This article is for educational purposes only and does not replace a conversation with your physician. Treatment decisions should always be made together with your care team based on your individual history, exam findings, and imaging. If you have questions about whether this procedure is right for you, please schedule a consultation.