PRP Injections for Arthritis and Tendon Pain: What the Research Shows

Platelet-rich plasma, or PRP, uses your own blood to treat joint and tendon pain. It has become one of the most talked-about injections in orthopedics. Here is a balanced look at what the research shows, where it can be used, and how it compares with steroid injections.

What PRP is

We draw some of your blood, spin it in a centrifuge to concentrate the platelets, and inject that concentrate where it is needed. Platelets carry growth factors and other proteins involved in healing. Because PRP comes from your own body, there is no steroid and no foreign drug in the injection.

I believe in PRP. In my experience, it helps most of my patients with arthritis.

PRP for knee arthritis: what the studies show

Compared with hyaluronic acid (gel) injections: pooled analyses of randomized trials favor PRP. In one analysis with about 11 months of follow-up, patients who received PRP improved 44.7% on a standard arthritis score, compared with 12.6% for hyaluronic acid.
Compared with steroid injections: a review of 8 trials and 648 patients found PRP better at reducing pain, stiffness and loss of function at 3, 6 and 9 months, with the largest difference at 6 to 9 months. In that review, three PRP injections a week apart did better than a single injection over 12 months.
Benefits tend to build over time. Another analysis found the advantage of PRP was small early on and became clinically meaningful at 6 to 12 months.
Not every study is positive. A well-designed 2021 trial of 288 patients with mild to moderate knee arthritis found that pain improved in both groups, but PRP was not significantly better than a saltwater (placebo) injection at 12 months, and it did not change cartilage on MRI.

Part of the difference between studies may come from how PRP is prepared. Products differ in platelet dose, white blood cell content and the number of injections, and there is not yet one standard recipe.

Fewer steroid-related risks

Steroid (cortisone) injections can give fast relief, but they have known downsides, especially with repeated use:

In a 2-year trial, a steroid injection into the knee every 3 months led to more cartilage loss than saltwater injections, with no difference in pain.
Steroids can temporarily raise blood sugar, which matters for people with diabetes. In that same trial, the steroid group had a small rise in their long-term blood sugar marker (HbA1c).
Repeated steroid injections near tendons can weaken tendon tissue.

PRP avoids these steroid-specific effects because it contains no steroid. Its most common side effect is a temporary flare of soreness after the injection, which in one trial usually lasted 1 to 2 weeks.

Not just for joints: PRP for tendons

PRP can be injected into a joint, and it can also be injected into or around tendons, where chronic tendon pain is common:

Tennis elbow: in a randomized trial of 100 patients, those treated with PRP were more often successfully treated at 2 years than those given a steroid injection. The steroid group felt better first, but their function returned to where it started, while the PRP group kept improving.
Outer hip pain (gluteal tendinopathy): in a randomized trial of 80 patients, a single PRP injection gave greater improvement at 12 weeks than a single steroid injection. The two were similar at 2 and 6 weeks.
Other tendons such as the patellar, Achilles and rotator cuff tendons are also treated with PRP, but the results there are more mixed.

Photo: Mezidi Zineb on Unsplash

Why dose matters: more platelets, more effect

Not all PRP is the same. The number of platelets delivered to the joint or tendon, the dose, appears to matter. In a randomized trial of 150 patients with moderate knee arthritis, PRP containing about 10 billion platelets gave better results than hyaluronic acid that lasted to 1 year, and the authors concluded that this platelet count was key to a lasting effect. A 2026 review of 62 trials found that PRP made from a larger blood draw (40 mL or more), a stand-in for a higher platelet dose, was linked to bigger improvements.

That is why we use the Cervos PRP system. We draw 80 cc of your blood and concentrate it down to about 5 cc of PRP, roughly 15 times the platelet concentration of your blood. Many PRP kits start with a much smaller blood draw, so they deliver fewer platelets.

What you eat matters, too

PRP is made from your own blood, so what is in your blood on the day of your injection goes into your PRP. A heavy, high-fat meal can temporarily raise inflammatory markers in the blood. In one small study, an inflammatory marker (IL-6) rose about 70% four hours after a plain burger. In another, a large fast-food breakfast triggered inflammation in white blood cells within an hour. Not every study finds this effect after a single meal, and no study has yet shown that a meal changes PRP results, but it makes sense to give your PRP the best starting material.

Before your PRP injection:

Skip the burger and fries. Choose a light meal, such as fruit, vegetables, whole grains and lean protein.
Drink plenty of water.
Ask us before taking anti-inflammatory medicines such as ibuprofen or naproxen. They affect platelet function and are usually paused before PRP.

What the guidelines say

Guidelines remain cautious. The American Academy of Orthopaedic Surgeons’ 2021 knee arthritis guideline lists PRP as an option that may reduce pain and improve function, but rates the strength of that evidence as limited because study results vary. Researchers continue to work on the best preparation, dose and patient selection.

Is PRP right for you?

PRP may be worth considering if you have arthritis or chronic tendon pain that hasn’t improved with exercise and other first-line care, if you want to avoid or limit steroid injections, or if you have diabetes and want to avoid steroid effects on blood sugar. PRP is often not covered by insurance, so cost is part of the decision.

Like any injection, PRP works best as part of a plan that includes strengthening. You can read more in Stronger Knees Are Functional Knees and Hyaluronic Acid Injections for Knee Arthritis. If you’d like to know whether PRP fits your joint or tendon problem, book a visit and we’ll go over your options together.

References

This article is for general education and isn’t medical advice. For advice about your own condition, please book a visit.