PRP injections

What is PRP?

PRP stands for platelet-rich plasma. It comes from your own blood. A small amount is drawn from your arm and spun in a machine called a centrifuge, which separates the blood into layers. The layer with a higher share of platelets is then collected and injected into the sore area.

Platelets are the blood cells that help with clotting, and they release proteins involved in the body’s normal response to injury. The idea behind PRP is that placing more of them in one spot might ease symptoms. That idea makes sense on paper, but whether it helps in real patients is a separate question. Studies have given mixed answers.

PRP is also not one single product. Kits and methods differ in how many platelets and white blood cells end up in the syringe. That makes it hard to compare studies, and a result from one version may not apply to another.

Does PRP work for knee arthritis?

The honest answer is that the evidence is mixed, and experts disagree.

The strongest argument against it comes from a large trial called RESTORE. It included 288 people aged 50 or older with mild to moderate knee arthritis. They had three weekly injections of either PRP or salt water (a placebo). After 12 months, pain had improved by 2.1 points with PRP and 1.8 points with placebo, on a 0 to 10 scale. That gap was small, and it could have been due to chance. The two groups also lost about the same amount of cartilage, and PRP did not protect it. The authors concluded that their findings do not support PRP for knee arthritis (Bennell, 2021).

Notice that both groups improved. This is why placebo-controlled trials matter. Pain often gets better after any injection, even salt water, so a person’s improvement after PRP does not prove that PRP caused it.

On the other side, a European expert consensus regarded PRP as a valid option for knee arthritis, mainly for mild to moderate disease. It also said PRP seems to last longer than a corticosteroid injection (Laver, 2024). Keep in mind what a consensus is: expert judgment, not a single test. Only 9 of its 28 statements had high-level scientific support, and 12 were graded as expert opinion.

So PRP is a reasonable thing to discuss if you have mild to moderate knee arthritis and understand that it may not help. It is not a proven treatment.

Does PRP work for tendon problems?

This is also unsettled. The evidence on tennis elbow is not encouraging. A Cochrane review of 32 studies with 2,337 people looked at PRP and whole blood injections. Compared with placebo, they probably give little or no meaningful benefit for pain or function. Average pain was only 0.16 points better on a 0 to 10 scale at three months. The authors did not support using them for this problem (Karjalainen, 2021).

That review covers one tendon. Its result may not carry over to the shoulder, the hamstring, or the hip. For gluteal tendons, see the gluteal tendon guide. If you are considering PRP for a tendon, ask what has been studied for your exact problem.

Can PRP regrow cartilage or help me avoid surgery?

Please be cautious about these claims. In RESTORE, PRP did not change cartilage volume compared with placebo (Bennell, 2021). None of the studies on this page shows that PRP regrows tissue, or that it prevents or delays surgery.

What is bone marrow aspirate?

Bone marrow aspirate is another option Dr. Pareek uses where appropriate. After numbing the skin and bone, a needle draws a small amount of marrow, usually from the pelvis. It may then be spun to concentrate it before it is injected.

The evidence here calls for the same caution. In a large randomized trial, 480 people with knee arthritis received a cell-based injection or a corticosteroid. One year later, none of the cell-based injections, including bone marrow concentrate, did better than the steroid or each other. MRI arthritis scores did not change significantly in any group. No serious procedure-related problems were reported (Mautner, 2023).

What happens at a visit, and what does it cost?

First comes a talk about whether an injection makes sense for you at all. On the day of an injection, blood is drawn, processed, and injected, sometimes with ultrasound to guide the needle. You may be asked to avoid certain pain medicines beforehand, so check with the office. The number of injections varies.

Injections can cause pain, and they carry a small risk of infection (Karjalainen, 2021).

Insurance often does not cover PRP or bone marrow injections. Please ask the office about coverage and cost before you decide.

Where can I see Dr. Pareek?

Dr. Pareek sees patients at HSS in New York and at HSS in New Jersey. Bring any X-rays, MRI images, and reports you already have. If you want a fresh look at your options, here’s how a second opinion works.

What does recovery look like?

These are typical ranges. Your surgeon’s plan comes first, and recovery varies from person to person.

• First few days: Expect some sorenessThe injected area is often sore, and it can feel worse before it feels better. Take it easy and follow the instructions you are given, including what to take for pain.
• First few weeks: Ease back inMost people return to normal daily activity early and build back up. Any limits on sport or therapy depend on what was treated, so follow your plan.
• Weeks to months later: Judge the resultGive it time before you judge it. Some people notice relief and others do not. Your follow-up visit is the time to decide together what comes next.

Sources

1. Bennell KL, et al. Effect of intra-articular platelet-rich plasma vs placebo injection on pain and medial tibial cartilage volume in patients with knee osteoarthritis: the RESTORE randomized clinical trial. JAMA 2021;326:2021-2030.
2. Laver L, et al. The use of injectable orthobiologics for knee osteoarthritis: a European ESSKA-ORBIT consensus. Part 1: blood-derived products (platelet-rich plasma). Knee Surg Sports Traumatol Arthrosc 2024;32:783-797.
3. Karjalainen TV, et al. Autologous blood and platelet-rich plasma injection therapy for lateral elbow pain. Cochrane Database Syst Rev 2021;9:CD010951.
4. Mautner K, et al. Cell-based versus corticosteroid injections for knee pain in osteoarthritis: a randomized phase 3 trial. Nat Med 2023;29:3120-3126.