PRP Knee Injection : We Know More about PRP than Knee Replacement
If you’re considering a PRP knee injection the first question to ask is whether we know this procedure works. Given that many patients want PRP injections to avoid a knee replacement, let’s focus on whether PRP injections work as well as, worse, or better than knee replacement by looking at the research behind each.
What is PRP?
PRP stands for Platelet-Rich Plasma. This is a product made from your own blood where your platelets are concentrated in your plasma. Platelets contain healing growth factors that release their payloads over time to assist in tissue repair (1).
What is a PRP Knee Injection Used For?
A PRP knee injection is usually used to help arthritis pain. The procedure typically involves using ultrasound or real-time x-ray imaging (fluoroscopy) to precisely inject PRP into the damaged knee joint. The knee will sometimes be swollen for a few days and then most patients respond by a few weeks. These injections can provide pain relief and improve knee function for 1-2 years in most patients. Also different than steroid injections which can harm knee cartilage (4, 22), PRP knee injection is thought to help knee cartilage (2).
Understanding Medical Research
Medical research can be graded like a report card (3). The studies that are randomized controlled trials (RCT) get higher grades than other types of research. The absolute best type of research is one where a fake or sham treatment is used and neither the doctor nor patient knows who got which treatment. For surgeries this is more difficult, so for sham procedure studies, usually only the patient doesn’t know if they got the real surgery or one that was faked.
How Good is the Research Showing that PRP Works?
We have 27 RCTs to date on PRP knee injection when used to treat arthritis. Those are studies that compared PRP to common treatments like steroid shots, hyaluronic acid (HA) injections (knee gel shots), or physical therapy (5-21). PRP was as good as HA or better and better than steroid shots or exercise. We even have studies that show that PRP works when compared to a faked treatment like saline.
How Does PRP Knee Arthritis Research Compare to Knee Replacement?
You may not have a sense that 27 RCTs showing that PRP knee injection works for arthritis is a good amount, so let’s compare that amount and quality of research to a common treatment for knee arthritis. We have more than 600,000 knee replacement surgeries in the US that happen each year at an approximate cost of $49,500 each or approximately 30 billion. So how many RCTs do we have on knee replacement? Two. In fact, unlike most of the PRP RCTs shown above, neither of these was a higher quality sham study. Meaning the patients knew they were getting a knee replacement, which in and of itself would be a huge placebo effect. Meaning, big surgeries have the effect of convincing people they must be better even when the surgery didn’t help at all (24).
In one of these two studies (23), the results of knee replacement weren’t impressive. meaning, you needed to replace 5-6 knees to ensure that one patient reported a 15% functional improvement or better. 3 in 4 of the patients who were randomized to get physical therapy over knee replacement ended up canceling their surgery. Hence, when compared head to head, we have much more high-quality information showing that PRP works when compared to knee replacement.
Is PRP Knee Injection Covered by Insurance?
For most Americans, the answer is not yet. While certain groups like Regenexx (author of this blog post) have gotten coverage from many self-insured employers, that coverage right now extends to only about 10% of the total patients with private health insurance. Why then is a knee replacement covered? Instuitional inertia is the only answer that makes sense.
The upshot? PRP knee injection should be a real contender when you have knee arthritis. We’ve been using this treatment for 15 years with great success and the research now backs up that it works.
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