PRP and Biologic Injections: 35 Questions Patients Ask

Platelet-rich plasma (PRP) is a concentrated preparation made from your own blood. Platelets are blood cells that help with clotting and release proteins called growth factors that are involved in healing. In PRP, the concentration of platelets can be 5 to 10 times higher than in normal blood.¹ See our PRP therapy page for more detail.

A small amount of blood is drawn from your arm, as for a routine blood test. The blood is spun in a machine called a centrifuge, which separates the platelets and plasma from the red blood cells. The concentrated platelets are then injected into the joint, tendon or injured area.¹ The whole process is usually done during one visit.

Leukocytes are white blood cells. Depending on how it is prepared, PRP can keep most of the white cells (leukocyte-rich) or have most of them removed (leukocyte-poor). Leukocyte-poor PRP is generally used for joints such as an arthritic knee, while leukocyte-rich PRP has been studied mainly for chronic tendon problems. The type Dr. Dold recommends depends on what is being treated.

No. PRP is made from blood and contains platelets, not stem cells. Stem cell claims are a separate topic, covered below and on our stem cell injection facts page.

Growth factors released by platelets are thought to calm inflammation and support the body’s healing response in tendons and joints. The exact way PRP works is not fully understood, and it does not regrow lost cartilage. In arthritis, the goal is less pain and better function, not a new joint surface.

The evidence is mixed. A 2024 meta-analysis (a study that pools the results of many trials) of randomized trials including 1,993 patients found that PRP was more likely than hyaluronic acid (gel) injections to give a successful result for knee osteoarthritis.² Many people with mild to moderate knee arthritis report less pain, but not everyone improves. See knee osteoarthritis for all treatment options.

Yes. In the RESTORE trial, published in JAMA in 2021, 288 adults with knee arthritis received either three weekly leukocyte-poor PRP injections or three saline (salt water) placebo injections. At 12 months, pain improved in both groups, and there was no significant difference in pain or in cartilage volume on MRI between PRP and placebo.³ Results like this are one reason PRP for arthritis is still debated.

PRP is not one product. Studies use different machines, platelet and white cell concentrations, numbers of injections and types of patients, which makes them hard to compare. Placebo injections also often help people feel better for a while.³ Dr. Dold will go over the evidence that applies to your situation.

No. PRP has not been shown to regrow worn-away cartilage. In the RESTORE trial, PRP did not change cartilage volume on MRI compared with placebo.³ Dr. Dold was first author of a 2014 systematic review of PRP for cartilage problems, which looked at the clinical research available at the time.⁴

Results are mixed. In one randomized trial of 100 patients, 73% of those treated with PRP had meaningful pain improvement at 1 year, compared with 49% of those treated with cortisone.⁵ However, a systematic review that compared PRP with other control injections, including saline, concluded that PRP did not show a clear benefit in most high-quality trials.⁶ PRP is one option for tennis elbow that has not improved with rest, bracing and physical therapy.

The American Academy of Orthopaedic Surgeons describes results for Achilles tendinitis and jumper’s knee (patellar tendinitis) as promising but not clearly better than traditional treatment.¹ For outer hip pain from gluteal tendon problems, see PRP for hip pain.

Sometimes. PRP can be added during rotator cuff repair, but the American Academy of Orthopaedic Surgeons notes that studies have shown little or no benefit for PRP during rotator cuff repair and ACL reconstruction.¹ See our rotator cuff questions page for more on rotator cuff surgery.

PRP is sometimes used for hip arthritis, often with ultrasound guidance to place the needle accurately. See PRP injections for hip pain for details on the evidence for the hip.

Bone marrow aspirate concentrate (BMAC) is made from a small amount of your own bone marrow, usually taken from the back of the pelvis with a needle after numbing medicine. The marrow is spun in a centrifuge and the concentrated portion is injected the same day. See BMAC for more detail.

BMAC contains a mix of cells, growth factors and proteins. Only a tiny fraction of its cells are stem cells, and how BMAC works is not fully understood, so calling it a “stem cell injection” overstates what it is.

The evidence is limited. In a placebo-controlled trial of 25 patients who had BMAC in one knee and saline in the other, pain improved in both knees at 12 months with no clear difference between them, and MRI showed no sign of cartilage regrowth.⁷ Larger, higher-quality studies are still needed.

The U.S. Food and Drug Administration (FDA) warns that products sold as stem cells, fat-derived cells, umbilical cord blood, amniotic fluid, Wharton’s jelly and exosomes are not approved to treat orthopedic conditions such as osteoarthritis, tendonitis, back pain, hip pain, knee pain or shoulder pain.⁸ The FDA has reported serious harms from unapproved products, including blindness, tumor formation and serious infections.⁸ Read our stem cell injection facts page before considering any of these products.

No. No stem cell product is FDA-approved to treat arthritis or other orthopedic conditions.⁸ The American Academy of Orthopaedic Surgeons notes that unproven stem cell therapies can be particularly unsafe.⁹ Be cautious of any clinic that promises to regrow cartilage or avoid surgery.

PRP is prepared with devices cleared by the FDA, but the FDA has not approved PRP injections to treat any specific orthopedic condition. Their use is considered off-label, which is common in medicine.

Usually not. The American Academy of Orthopaedic Surgeons notes that few insurance plans provide even partial payment for PRP, and many orthobiologic treatments are not covered by insurance.^1,9 PRP is typically an out-of-pocket cost, while cortisone and gel (viscosupplement) injections may be covered.

Costs vary by treatment, doctor and facility.⁹ Please call 469-850-0680 for current pricing before your visit. Ask how many injections are being recommended, since that affects the total cost.

Many patients use Health Savings Account (HSA) or Flexible Spending Account (FSA) funds for medical treatment, but eligibility depends on your plan. Check with your plan administrator. Our office can answer questions about paying for care.

Dr. Dold accepts most major insurance plans, including Medicare and Tricare. Please call 469-850-0680 to confirm your coverage. See our insurance page for plans we work with.

Your blood is drawn, the PRP is prepared in the office and the area is cleaned before the injection. Ultrasound may be used to guide the needle into the right spot, especially for the hip and for tendons. You go home the same day.

You may feel pressure and discomfort during the injection. Pain at the injection site can increase for the first week or two afterward.¹ Ice and rest help. Dr. Dold’s office will tell you what to take for pain.

Often, yes. Anti-inflammatory medicines (NSAIDs) such as ibuprofen, naproxen and aspirin affect how platelets work, so patients are commonly asked to pause them for a period before and after a PRP injection. Dr. Dold typically asks patients to stop these medicines 1 week before and 2 weeks after a PRP injection. Do not stop a blood thinner or any prescribed aspirin without talking to the doctor who prescribed it.

Expect soreness and some swelling for a few days. Dr. Dold will give you instructions for activity, which may include a short period of relative rest and then a gradual return, often with physical therapy for tendon problems. Avoid hard exercise on the treated area until you are cleared.

PRP is not a quick fix. Any benefit may take several weeks to appear.¹ Your follow-up visit is a chance to check how you are doing and decide on next steps.

It depends on the condition. For knee arthritis, a series of 2 to 3 injections is common; some tendon problems are treated with a single injection. Dr. Dold will explain the plan he recommends for you.

The most common side effect is temporary pain and swelling at the injection site. The American Academy of Orthopaedic Surgeons notes that the rate of other problems, such as infection, tissue damage and nerve injury, appears similar to that of cortisone injections.¹ Because PRP comes from your own blood, allergic reactions are unlikely.

PRP may not be appropriate if you have certain blood or platelet disorders, an active infection, some cancers, or if you take blood thinners that cannot be paused. It is also unlikely to help severe, bone-on-bone arthritis, a fully torn tendon that needs repair, or a mechanical problem such as a loose piece of cartilage that locks the knee.

It depends on the condition and your goals, and each has trade-offs. In one tennis elbow trial, PRP gave better results than cortisone at 1 year.⁵ Dr. Dold will review the pros and cons of each option with you.

PRP does not reverse arthritis or regrow cartilage.³ For some people with mild to moderate arthritis it may ease symptoms for a time. If your arthritis is advanced, Dr. Dold will talk with you about other options.

Yes. For tendon problems and arthritis, PRP is usually one part of a plan that also includes strengthening exercises, activity changes and, if needed, weight loss. Injections are meant to be combined with these basics, not to replace them.

Call 469-850-0680 right away if you have fever, chills, increasing redness or warmth, drainage from the injection site, or pain and swelling that keep getting worse after the first few days. These can be signs of infection, which is rare but needs prompt care.