By Sam McCommon and Michael K. Fujinaka, MD

The body’s joints are an easy thing to take for granted. When everything functions as intended, you’ll barely notice at all. What’s more, these same joints — the ones that allow you to move at all — are sadly undercelebrated body parts. You’ll never see someone posing for a gym selfie that highlights their nimble knees, or mobile rotator cuffs, or structurally sound ankles.
But when these joints begin to wear out — as they do for so many — people certainly take notice. It’s easy to forget how often you use your knees until they hurt. And osteoarthritis (OA) in the knees can cause significant pain to sufferers.

This condition and the pain that accompanies it are unfortunately nothing new. Since the dawn of time, any creature with joints may eventually suffer joint degradation due to a host of reasons, and humans are no exception. In fact, we’re more susceptible to knee problems than many other mammals to knee problems because we’re true bipeds, so our knees carry significant weight. We are, however, an exception in that we can figure out ways to prevent and even heal these joint problems.

One such treatment that is growing in popularity is platelet rich plasma (PRP) injections. PRP knee injections have garnered significant support from research and may prove to be a valuable ally in the fight against OA.
So, follow along as we dive into the science behind PRP knee injections for OA and try not to get lost in too many three letter acronyms (TLAs). But first, let’s make sure we’re all on the same page.

Quick‌ ‌PRP‌ ‌Injection‌ ‌Background‌ 

If this is your first time reading about PRP, fear not. You can check out our FAQ here for a more elaborate question and answer format, but consider this section a quick primer.

Platelets are one of the three main components of your blood, along with red blood cells and white blood cells. These three parts all flow through your body in a fluid called plasma. That’s blood summarized in two sentences.

Platelets play a large role in the healing process. They cause blood clotting and they also contain growth factors, which encourage swelling, increased blood flow, and the production of new tissue.

The concept behind PRP is this: By concentrating platelets in plasma — making the plasma “rich” in platelets — this natural healing could be turbocharged. A person’s own platelets could be concentrated in their own plasma and reinjected into damaged areas to encourage healing.

If you’d like to find out just how such a procedure works, check out our article on PRP procedures.

Studies Supporting PRP Injections for Knees

As a 2015 editorial in the Journal of Arthroscopic and Related Surgery flatly states, “Platelet-rich plasma improves knee pain and function in patients with knee osteoarthritis.”

Of course, it’s a more nuanced topic than just that. Much depends on the knee, the patient, the medical practitioner, the concentration level of platelets, other treatments, any physical therapy that follows, and more. But if you were to stop reading right now, the above statement could be your key takeaway.

But let’s look into that nuance and find out some of the key points that make PRP tick. After all, curiosity is the basis of science — and, heck, of knowledge in general.

PRP Concentration Levels

One potentially interesting variable in PRP therapy is the amount of platelets concentrated in the blood. Essentially, there are two methods of concentrating platelets that lead to different amounts. One method, using a single spin cycle, leads to concentrations roughly three times the normal rate, while the other, which uses a double spin cycle, can produce concentrations around five times and even up to ten times normal.

The lower concentrations take less time to produce — around ten minutes — which means less time spent in the clinic. Higher concentrations may take around a half hour, and may also require an anticoagulant to prevent the blood from clotting.

One study indicated that a single injection of PRP concentrated at ten times the normal rate was more effective at treating early KOA than two injections of PRP concentrated at three times. However, both were far more effective at relieving pain and improving mobility than a saline injection. Additionally, the study noted that the effects of the injection wore off after around six months.

As a brief aside, while saline may sound like it’s purely intended to be a placebo, it has actually shown some limited value in treating osteoarthritis. So, the study was not simply comparing PRP to an inert placebo.

PRP concentration levels and injection methods are not yet standardized in practice, so the specialist you visit will need to determine what’s right for you. However, patients can take comfort in the fact that such a specialist exists at all.

Does PRP Work for Early or Late-Stage KOA?

Evidence shows that PRP can be effective for both early- and late-stage KOA. Most studies have focused on younger patients with early or mild KOA, usually with positive results.

However, recent evidence has shown PRP therapy can be effective for all stages of KOA. This is excellent news for sufferers of late-stage KOA, who often have to deal with significant pain and loss of mobility.

One 2017 study in the Journal of Orthopedic Sports Medicine demonstrated that a single shot of PRP was as effective in inducing pain relief and improving the overall quality of mobility in older KOA sufferers as a shot of cortisone. Since the effects of PRP lasted longer than cortisone — six to twelve months on average — the authors of the study suggested a cyclical regimen of PRP treatment for older patients with late-stage KOA, perhaps once or twice per year.

Platelets and White Blood Cell Counts

We can begin this section simply by saying the interaction between PRP and white blood cells (leukocytes or WBC) is not entirely understood. However, some evidence shows that PRP that has been filtered of leukocytes is more effective than PRP that still contains normal amounts. For now, there have not yet been studies that compare leukocyte-rich PRP versus leukocyte-poor PRP. Watch this space for more developments.

Hyaluronic Acid and PRP: Working Together

Hyaluronic acid is a vital and common substance in the human body that plays a large role in helping tissue remain healthy. It’s found in abundance in the skin and connective tissue, for example, and is often used in beauty products and even injections because of its ability to bind to huge amounts of water, making skin look healthy and young.

Hyaluronic acid injections have shown promise in treating osteoarthritis as it can improve lubrication while reducing inflammation, leading to better physical function. Hyaluronic acid can help regenerate cartilage. That’s some good news.

What may be even better news is hyaluronic acid can be combined with PRP to reduce the effects of knee arthritis. One 2018 study in Experimental and Therapeutic Medicine demonstrated that, when combined, hyaluronic acid and PRP reduced the symptoms of KOA significantly more than when each was used individually.

Considering that both hyaluronic acid and PRP have extremely low risks associated with them, one might wonder if combining them could lead to any adverse risk. Fear not: A meta analysis showed that combining the two leads to no increased risk of adverse effects compared to each on its own — which, as mentioned, is very low.

Time to Speak to a Specialist?

The evidence is mounting: Platelet rich plasma therapy can be a valuable treatment for knee osteoarthritis. In addition to its ability to reduce pain and encourage healing, it’s non-invasive, fast, and — best of all — can help a person avoid knee surgery.

The effects of PRP can take up to 12 months to be fully realized for some, while others may note it much faster. The point, however, is that it’s a long-lasting and natural procedure that relies on your body to heal itself. No anti inflammatory medications can claim that, nor can any surgery.

If you think your knees may benefit from PRP therapy, set up an appointment with your local, friendly pain specialist. Bear in mind that the consultation for PRP treatment is covered by insurance, so no need to hesitate due to cost. 

Call 650-667-2322 to set up a consultation with Apex Pain and Wellness. We’ll be more than happy to help guide you through the process — and you’ll be happy you made the call.