Category: Knee Pain Treatments

How Long Should I Keep Getting Knee Injections Before Considering Other Options Like GAE?

Posted on by kaz

Wondering how long knee injections should be tried before exploring other treatments like Genicular Artery Embolization (GAE)?  Learn how injections work, how long they last, when they stop being effective, and when its time to consider minimally invasive alternatives.

If Your Injections Are not Lasting, You are Not Alone

It can be frustrating when knee injections offer less relief over time, shorter periods of benefit, or no improvement at all.  Many may wonder “how many injections should I try before moving on to something else?”  The answer is surprisingly consistent across orthopedic, rheumatology and interventional radiology guidelines for care. Our thought is that if injections are not providing meaningful or lasting relief after 1-3 rounds, its time to consider other options.

Understanding How Knee Injections Work (an Why They Stop Working)

Knee injections do not “fix” arthritis, but rather temporarily reduce inflammation or improve lubrication. They work best in early to moderate osteoarthritis and tend to lose effectiveness at the disease progresses.  Here is how each type of injection works:

  1. Corticosteroid Injections (CSI)
    1. Reduces inflammatory chemicals inside the knee join
    2. Offer relief anywhere from 2-8 weeks, sometimes longer in mild cases
    3. Often loses effectiveness after repeated use because inflammation becomes chronic or less steroid responsive
    4. Repeated (more than 3-4 injections per year) steroid injections may accelerate cartilage thinning if overused. Boston University OA Initiative Study, 2017 found increased cartilage loss in some repeated use patients.

When to stop CSI:

  1. If the last 1-2 injections provided less than 4-6 weeks of relief
  2. If pain returns quickly even with rest or medication
  3. If injections are needed more than 3 times per year
  4. Hyaluronic Acid (HA)/ Gel Injections
    1. Brand names include Synvisc, Monovisc, Euflexxa, Orthovisc, Gel-One.
    2. They help by improving join lubrication, reducing friction and possibly calming mild inflammation. They work best when some cartilage is still present and join space is not severely narrowed.
    3. Relief may last 3-6 months, sometimes up to 12 months in early disease.
    4. Research show that patients with advanced osteoarthritis often get little to no meaningful improvement.  Cochrane Review, 2015 found modest benefits in early Osteoarthritis (OA) but minimal help in late OA. 

When to stop HA injections:

  1. If 1-2 rounds lead to no measurable improvement
  2. If pain persists with daily activities despite treatment
  3. If swelling and stiffness return quickly
  4. PRP (Platelet-Rich Plasma) Injections
    1. PRP may help with early arthritis by reducing inflammation and supporting cartilage metabolic health. However, PRP results vary widely depending on technique and patient factors.
    2. PRP may loose effectiveness for many reasons. If the arthritis is moderate to advanced OA, when the joint has significant inflammation or bone marrow lesions and when mechanical alignment is an issue.  American Journal of Sprots Medicine, 2019 found that PRP works best for mild OA and loses benefit for progressive arthritis.

When to stop PRP:

  1. If 1-2 treatments offer little improvement
  2. If daily function or walking is still limited
  3. If swelling and stiffness persist

How Do You Know When It’s Time to Consider GAE?

Genicular Artery Embolization is not a first line treatment, but it becomes a strong option when you’ve tried 1-3 injections without lasting relief. It is also something to consider when you are not ready for knee replacement surgery, or you want to delay surgery, or if you cannot undergo surgery due to medical risks and other reasons or if the pain is out of proportion to x-ray findings.  If you have signs of synovitis (inflammation), GAE primarily targets abnormal blood vessel growth that fuels this inflammation. An MRI or ultrasound may show synovial hypertrophy, joint lining inflammation and increased blood flow. All of which can help to determine if you will benefit from GAE.  Lastly, if you want to reduce pain without steroids or repeated injections, GAE may be the options to choose.  GAE provides longer lasting relief, often 1-3 years, by reducing the blood vessels that feed chronic inflammation.  A 2023 study in Journal of Vascular Interventional Radiology showed that there is up to 70% reduction in pain. There is improved function in 12-24 months and MRI will show reduction in synovitis.

How Many Injections Are “Too Many”?

Here is a simple guideline used by providers that you may want to keep in mind.

  1. If injections work well then continue for 6-12 months. You should have pain relief that is meaningful and that is improving your quality of life.
  2. If injections helped before but don’t anymore then you should consider stopping after 2-3 attempts. This usually means inflammation has become persistent and the joint is no longer responding.
  3. If injections never helped then no need to repeat a treatment that is not effective for your type of arthritis.

What Comes After Injections?

When injections stop working, you may want to consider other options:

  1. Physical therapy & strengthening
  2. Targeted bracing for alignment support
  3. Anti-inflammatory medications
  4. Weight management strategies
  5. MRI or ultrasound to understand the source of the pain
  6. Minimally invasive options like Genicular Artery Embolization that are especially helpful for patients with persistent inflammation despite “mild to moderate” X-rays findings.

You should not feel stuck cycling through injections that are not helping. In most cases, if injections don’t provide lasting relief after 1-3 attempts, it’s appropriate to consider other treatments like GAE. Your pain, function and quality of life, and not just your X-ray, should guide treatment decisions.

Citations

  1. McAlindon T. et al. Corticosteroid injection and cartilage loss in knee OA. JAMA. 2017.
  2. Bannuru R. et al. Visco-supplementation for knee OA. Cochrane Review. 2015.
  3. Filardo G. et al. PRP effectiveness in knee OA. AJSM. 2019.
  4. Okuno Y. et al. Synovitis reduction after GAE. JVIR. 2023.
  5. Padia S. et al. Mechanisms of GAE in knee osteoarthritis. Techniques in Vascular & Interventional Radiology. 2023. 
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