Do PRP Injections Work?

The topic of PRP (platelet-rich plasma) injection therapy comes up quite often when knees, shoulders, or elbow injuries just aren’t healing as expected. The pros, cons, and anecdotal experiences are shared quite often in the sports and tactical medicine arenas. I’m intrigued by PRP, because I’ve tried it myself and have referred clients for the procedure. 

However, PRP is a controversial topic full of “gray” areas because recovery from injury depends on so many different things working together! It’s never just one thing that completely restores someone back to full function after an injury. In this article, I will explain some things I know about PRP treatments, and how I’ve seen them used to treat muscle and joint injuries. I will also share my own experiences with injections. 

What are PRP injections? 

PRP stands for platelet-rich plasma, a component of your blood that can be separated out and injected into different areas of the body, typically soft tissues, including muscles, ligaments, and tendons. Platelets aid in wound healing and the thought is that dropping them off at the site of tissue injury will help accelerate the healing process. The procedure is a three-step process. First, some of your blood is extracted from your arm. The blood is then spun in a centrifuge machine to separate the platelets from the rest of the blood. Finally, the concentrated platelet fluid is injected back into your body at the injury site using a hollow needle. 

Just poke it? 

Any needle (mechanical) technique inserted into a soft tissue structure can cause a local inflammatory (chemical) process that wakes up the cells responsible for doing the repair job. There are two main types of needle treatments for soft tissues. The first is dry needling, which using small acupuncture-type needles to create a tiny lesion that stimulates the healing process. The other is “wet” needling, where a substance designed to stimulate healing is injected from a hollow needle into the body. Examples of wet needling for healing purposes include prolotherapy injections with sugar or salt solutions, PRP, and stem cells. 

One thing to note about all of these techniques is that they usually poke the tissue repeatedly with the needle. This mechanical stimulation procedure is called fenestration. Fenestration stimulates the repair cells to respond. It’s like, as a kid, knowing you need to clean your room but not really getting around to it. When your mom actually walks in and starts rummaging through your stuff to clean it for you, you respond!

Having the tools but lacking the instruction manual 

A “successful” injury treatment is one that assists the body’s tissues in regaining strength and function needed for everyday life. The key to success with needling treatments is to pair them with other things known to improve tissue quality, including targeted, progressive exercise programs. The repair cells for body tissues depend on knowing the motions and loads – the mechanical stresses that the tissue will have to withstand – to understand how to repair it effectively. 

On their own, injectable treatments are like giving someone a set of tools to fix a TV but not giving them an instruction manual to complete the job. That person may know what a TV is, but how to go about repairing it requires more information.

There is another problem that is easily overlooked in conversations surrounding PRP injection treatment. Any weaknesses or compensations around the injured body part will render the treatment nearly useless. For example, suppose you have an injury to your knee, but you also have a stiff ankle or weak hip. You may get your knee healthy with PRP, but if you don’t fix the ankle or the hip, the knee problem is likely to return. 

Relief versus repair

But what about pain relief? Many people describe pain relief as a benefit of PRP injections. You may feel less pain at the injury site after PRP treatment, for many reasons. Unfortunately, it doesn’t mean the tissue is strong or ready, or that it will function as you need it to when you get back to your usual activity level. 

If PRP is to work by itself, the tissue and body parts must be stress-tested to ensure treatment success. It would be like patching a hole in the tire of your car but failing to check the alignment, and also failing to take it up to full speed for a couple miles to ensure the tire will hold. Unfortunately, most of the research on PRP fails to do these final tissue tests, so we just don’t know. 

The future of PRP

There is a ton of promise with injectables, and I try to keep up with the science as it develops. But unfortunately, at this time, injection treatments for soft tissue injuries aren’t Star Trek worthy yet. Platelets don’t work very well on the intended tissue, and they don’t directly solve the problem once they are onsite. 

Scientists are currently working at making scaffolds and cages that keep injectable chemicals nearby, so they don’t float way in body tissues. This can be a huge problem! In the future, perhaps we will also have “smart” injectable healing concoctions that know what needs to be done to get the tissue back to 100%, and stay put to see the job through. Until then, we’ll have to take a more combined treatment approach – pairing injection treatments with an intelligently designed exercise program.

My experience and current thoughts about PRP injections

I’ve seen some success with PRP injections in clients I’ve treated for stubborn tendon issues. These clients are in a rehab program with me but don’t respond to fenestration-type dry needling treatments that I provide. But, I’ve seen similar success when the needle is used ‘dry’ without the PRP. It’s just a bigger needle doing the poking. 

I can see some potential benefits for using PRP for large muscle tears to help speed up the healing process. This may be beneficial when tissue regeneration is needed instead of just a small repair. Muscle is a highly-active tissue, and there may be better ways to get the PRP fluid down deep into the “meat” where it can’t escape compared to tendons. Unfortunately, few of my clients in recent years have had access to rapid PRP injections to test out this treatment.

I have not seen the benefits of PRP injections for most ligament injuries I’ve treated. It seems similar to some of the issues with using PRP for tendons. Unfortunately, PRP injections did nothing for my own ligament injury despite the $1000+ out of pocket expense I paid to try it. And you can be sure I didn’t neglect the exercises!

The bottom line 

PRP injections may be helpful when:

  1. They are used to treat the right body parts, and 
  2. Tissue fenestration (stimulation) is a component of the procedure, and 
  3. They are paired with the correct exercise prescription, and
  4. Muscle weaknesses or other compensations have been eliminated

More information about PRP

For a good summary of the latest evidence, check out the article below. Initially published in 2014, this article has been updated several times and touches on some other injection treatments:

Does Platelet-Rich Plasma Injection Work?

Additional Research:  


Written by Dr. Rita Chorba, PT, DPT, SCS, ATC, CSCS

Board Certified Specialist in Sports Physical Therapy

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