When your knees hurt, every movement is a trial. Sitting down, standing, and walking become an exercise in perseverance as each step and movement produces a twinge of pain (or a slow, dull, constant ache). Knee pain can impact your daily life in a vicious cycle; the more pain you have, the less you move. The less you move, the more pain you have. Fortunately, there are a variety of treatment options to ease your pain and help heal and restore mobility. PRP therapy for knee pain is one of them. Here’s what you need to know about this procedure and its potential benefits.

What is a PRP injection in the knee?

The knee is a complex joint that supports the entire weight of the body with every step we take (and every move we make). Even if we care for our knees and practice proper alignment in all physical activity, over time, the joint begins to experience wear and tear. The femur, the tibia, the fibula, and the patella are the four bones of the knee. They are supported by ligaments and cartilage that stabilize the joint. The meniscus and fluid-filled sacs called bursae help to cushion and ease movement.

Because of the complexity of and pressure on your knee, knee pain from a variety of causes is possible. For some of these causes, one treatment option for knee pain is a PRP knee injection.

Platelet-rich plasma (PRP) treatment for the knee involves using a biological agent (the patient’s own platelets) to promote healing. Platelets are cell fragments in the blood that help it to clot. These fragments also contain proteins that can aid in healing. In a nod to the protein-filled aspect of platelets, PRP is also sometimes referred to as protein-rich plasma.

To extract platelets for injection, blood is taken from the patient and separated into blood cells and plasma. The platelet concentration increases as a result and is then added back to the plasma. This PRP treatment for knee pain is now ready for use.

Knee pain conditions

PRP knee injections can help treat the following conditions:

  • Patellar tendinopathy
  • Osteoarthritis in the knee
  • Anterior cruciate ligament (ACL) tears or injury
  • Tendonosis
  • Other forms of arthritis
  • Articular cartilage defects
  • Meniscal injury
  • Joint inflammation
  • Muscle strains

It is important to determine the cause of your knee pain before proceeding with PRP injections in order to evaluate the likelihood of a successful treatment.

Does PRP treatment for knee pain work?

The biggest question people considering a PRP treatment for knee pain have is whether or not it works. The not-so-simple answer is yes, no, and it depends.

A study in 2009 found that PRP injections reduced pain in patients with degenerative cartilage lesions. The effects took about six months, but the majority of patients found their pain reduced or eliminated. However, after 12 months, the pain began to return.

In 2012, another study looked at PRP knee injections as compared to hyaluronic acid injections for knee osteoarthritis. The study was small scale and focused on highly concentrated PRP injection. The results were positive, with PRP injections producing better results for younger, more active patients with mild knee osteoarthritis. As with the 2009 study, patients saw the best improvement between six and nine months, at which time pain began to re-emerge.

PRP research

More studies that have mixed results include the following.

  • Meniscal tears: A 2015 study found that PRP injections had about the same success in terms of pain relief as other biologic injections.
  • Chronic tendinopathy: A small study of 99 patients found that PRP treatment for knees was “moderately effective for treatment of recalcitrant tendinopathy,” but that, due to the small size, results were not conclusive.
  • Anterior cruciate ligament (ACL) tears: There were promising results when PRP injections were used in conjunction with surgery to repair tears to the ACL in this large-scale review of 11 studies that included 516 patients in all. The study focused on speed of healing, not pain relief, and found statistically significant healing times in six of the studies (but five studies found no benefit).
  • Knee arthritis: A more recent study looked specifically at PRP treatment for knee arthritis and found mixed results. In two of the 14 patients who completed treatment, pain was completely resolved, but the same number of patients had no change whatsoever in the frequency or severity of their pain.

For every study cited on this page, researchers continue to call for more research using double-blind trials with more subjects. Most current studies, positive or negative, utilize small sample sizes that are not easily translated to widely applicable use.

Challenges of PRP research

While there is some early promise when it comes to PRP injections for knee pain, why are treatment results so mixed and research studies so cautious?

Any time you opt for an interventional treatment that goes beyond what occurs outside the body (e.g., exercise and physical therapy), it is crucial to explore the possibilities of success and the likelihood of complications.

Proponents of PRP injections point out that although the platelets are coming from your own body, making them automatically bio-compatible, for some people, it may be too much of a good thing. The theory behind PRP treatment for knee pain is that if some platelets help with healing and regeneration, more must help more, right? While this is likely true for some types of injuries, this is not the case for every type of patient.

Other reasons that PRP injections may not work include:

  • Interaction with other drugs: Especially in emergency situations where steroids or local anesthetics are used, PRP therapy may not work and may actually be toxic to platelets
  • Not administered in conjunction with rehab: Most studies conclude that PRP injections work best when combined with physical therapy
  • Not enough platelets injected: As with any injected treatment, proper dosing is key
  • Too high of a concentration of platelets: Just as you can inject not enough platelets, the dose needs to be of a proper concentration, as too many concentrated platelets can be toxic
  • Unrealistic expectations: PRP therapy for knee pain is not an analgesic and should not be expected to completely and radically “cure” pain

Could PRP therapy help me? 

PRP treatment for knee pain has only been around since the 1950s. Even with positive anecdotal reporting from professional athletes, there is still much research to be done to pinpoint which conditions it treats and for whom it might work best.

It’s best to undergo this approach only after you’ve exhausted other pain-relieving measures like physical therapy or exercise. However, for some patients who have tried everything else, PRP treatments provide a promising new form of therapy that could help them get back to a life with less pain.

Will PRP Treatment For Knee Pain Help Me? | PainDoctor.com

What can I expect for PRP treatment for knee pain?

The first step in treatment is a consultation with a doctor who specializes in regenerative medicine. It is important to pinpoint exactly what is causing your pain to determine if PRP therapy for knee pain is an option, or if you might be better served by another treatment. A full medical history and physical exam will be conducted, and you will discuss what treatments you have already tried.

If you and your doctor determine that PRP injections are a good option, the next step is to draw blood from which platelets will be extracted. This is done as a standard blood draw. Once the platelets are extracted with a centrifuge, they will be combined with more of your blood.

Your doctor uses an ultrasound to pinpoint the precise location for the injection. The area to be injected is cleaned and sterilized, and the injection is administered. If the site is sensitive or deep, you may feel some pain during the injection. This should be brief. If you are concerned about pain, talk to your doctor before the procedure. There are pain relief options for the procedure itself.


After the injection, the injection site may be tender, and you may develop a small bruise. This is normal and should gradually disappear on its own.

Following the injection, your doctor will give you specific recovery guidelines. Always follow your doctor’s instructions, but in general, you should:

  • Avoid strenuous exercise for a week or two
  • Avoid anti-inflammatory drugs (with or without steroids) as this can interfere with the therapy
  • Wear any prescribed splints or stabilizers as directed
  • Use ice or cold/hot packs for swelling and redness
  • Keep your knee elevated at night

If you get physical therapy, increase your chances of a successful PRP treatment for knee pain by following that prescription as well. Patients with the best chance of healing and pain relief find that physical therapy is crucial to keep their knee mobile during the PRP treatments, while also building strength in the supporting muscles, ligaments, and tendons for longer-term pain relief.

Note that you may not begin physical therapy for a month or two after your injection. If this is the case, ask your doctor if there are light, low-impact activities you can do that can help with healing.

Although the chance of side effects is minimal, all medical intervention comes with some risk. Talk to your doctor if knee pain and swelling increases or if you suffer from further injury to your knee. If you experience fever and a feeling of being unwell, call your doctor, as this can be a sign of infection.

Side effects due to the platelets themselves are virtually non-existent, as the platelets are extracted directly from the patient.

How long does it take PRP to work?

Some people experience near immediate pain relief, but it is not clear if that occurs in conjunction with other concurrent therapies (e.g., exercise, rest, or physical therapy).

For others, they may experience pain relief and healing beginning around three months. Many patients find that they need more than one PRP injection. If there are no results after multiple injections, you’ll typically stop this treatment and explore other options.

Where can I learn more about PRP treatment for knee pain?

The knee is arguably the hardest working joint in the body. We demand a lot of it, and it shows over time. PRP treatment for knee pain is just one of a host of options you have when it comes to restoring the health and mobility of your knees.

If you are in the Phoenix Valley, Pain Doctor can help you explore treatment options for knee pain, including PRP injections. Our team focuses on a comprehensive pain management approach that incorporates non-invasive therapies, interventional procedures, and cutting-edge pain management techniques.

Get in touch today to let us help you find relief!

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