PRP therapy treats a damaged joint or tendon using a concentrate made from your own blood. A clinician draws a small sample, spins it in a centrifuge to separate the platelets from red cells, and injects that concentrate into the injured tissue under ultrasound or landmark guidance. Nothing synthetic goes in. Nothing comes from a donor.
Patients usually arrive at PRP after something else stopped working. Physical therapy plateaued, or the second cortisone shot wore off faster than the first.
Surgery is on the table but nobody is in a hurry to schedule it. That is the gap PRP occupies. Understand what it can and cannot do before you pay for it.
What is PRP therapy
PRP stands for platelet-rich plasma. PRP treatment and PRP therapy mean the same thing, and clinics use the two terms interchangeably.
Platelets are the blood cells responsible for clotting, and they also carry growth factors that direct tissue repair after an injury.
Concentrating them and placing them directly into a tendon or joint delivers a much higher dose of those signals than the body would send on its own to an area with poor blood supply.
Poor blood supply is the reason so many orthopedic injuries stall. Cartilage has no blood vessels at all. Tendons and the meniscus have very little.
An injury there gets a fraction of the healing signal that a cut on your arm receives, which is why a rotator cuff strain can drag on for a year while a skin wound closes in ten days.
What is a PRP injection
A PRP injection is a single office procedure that takes about 45 to 60 minutes start to finish. Draw volume and spin time depend entirely on the system.
The Selphyl system needs a 9 mL blood draw, about one standard tube, and spins for 6 minutes. Older systems pull 60 mL and run the centrifuge for 15.
Either way, what comes out is a few milliliters of plasma carrying a platelet count well above your baseline blood.
When the platelets are available to the tissue
Most PRP marketing talks about concentration. The more useful question is when those platelets are available to do anything.
Platelets release their growth factors within minutes of activation. A preparation that dumps its entire payload at once gives the tissue one short burst on day one, at a point when most of the repair cells that respond to those signals have not arrived yet.
Tendon and cartilage repair runs over weeks. A burst that is finished by Tuesday does not match that timeline, which is one reason results across PRP studies scatter so widely.
Selphyl approaches this by keeping fibrinogen in the preparation instead of filtering it out. The fibrinogen converts to fibrin and forms a matrix at the injection site, and that matrix holds the platelets in place and releases growth factors gradually over roughly 7 to 10 days.
The platelets stay where the needle put them and keep signaling while the repair response is building.
Concentration still counts. A 2025 meta-analysis in the American Journal of Sports Medicine covering 18 randomized trials and 1,995 knee osteoarthritis patients found that PRP above roughly 1,000,000 platelets per microliter produced meaningful pain relief holding through 12 months, while weaker preparations did not.
Concentration and duration are two separate variables, and a system can get one right and the other wrong.
How does PRP therapy work
The injected platelets release growth factors over several days. Those signals recruit repair cells to the site and shift the chemical environment inside a joint away from the inflammatory state that drives cartilage breakdown and pain.
Local blood vessel formation increases as well.
That process is slow. Most patients feel nothing for two to four weeks, and improvement continues building for three to six months.
Anyone promising same-week relief is describing a cortisone shot, which suppresses inflammation quickly and does nothing for the underlying tissue.
Orthopedic PRP therapy by body area
PRP injection therapy is used across most of the musculoskeletal system, though the strength of the evidence varies a lot by site.
PRP knee therapy
The knee has the deepest research base. PRP for knee arthritis and PRP therapy for osteoarthritis of the knee are the most studied applications, and the 2025 American Journal of Sports Medicine analysis found PRP beat placebo saline on pain at 3 and 6 months and on function at every follow-up point through a year.
PRP injection for arthritis works best in early to moderate disease, meaning Kellgren-Lawrence grade 2 or 3. Bone-on-bone grade 4 knees respond poorly, and a good PRP therapy specialist will tell you that before taking your money.
One knee study tracked structure alongside symptoms. Brian Halpern and colleagues at the Hospital for Special Surgery treated patients who had early knee osteoarthritis (Kellgren grade 0 to II) with a single 6 mL injection prepared using a fibrin matrix system, then tracked them for a year with clinical scores and MRI.
WOMAC pain scores dropped 41.7% at six months and 55.9% at twelve. At one year, 88% of patients had at least 25% improvement in pain. MRI told a similar story, with at least 73% of cases showing no change per compartment at one year, measured against longitudinal data where arthritic knees lose 4% to 6% of cartilage volume annually.
It was a small case series without a control group, published in Clinical Journal of Sport Medicine in 2012, so read it as a signal rather than proof.
PRP for meniscus tear is more limited. Degenerative tears in the outer third, where some blood supply exists, have shown response in smaller studies.
A displaced bucket-handle tear locking your knee needs arthroscopy, and no injection changes that.
PRP for shoulder pain and rotator cuff injury
PRP for rotator cuff injury is used mainly for partial-thickness tears and tendinopathy that has failed several months of physical therapy.
Full-thickness tears with retraction are a surgical problem. Where PRP has a clearer role in the shoulder is as an augment applied during rotator cuff repair surgery, which is a separate question from injecting it as a standalone treatment.
PRP for tennis elbow and elbow pain
Lateral epicondylitis has some of the most consistent data outside the knee. A 2023 systematic review in the Journal of Shoulder and Elbow Surgery pooling level 1 and 2 studies found corticosteroid injections outperformed PRP at 1 month, then PRP overtook them by 6 months.
A 2024 meta-analysis in the American Journal of Sports Medicine reached the same conclusion on long-term function and pain relief. PRP for tendonitis follows that pattern generally. Slower to start, better where it counts.
PRP for hip pain
PRP for hip pain covers two different problems. Gluteal tendinopathy and hip bursitis, both outside the joint, respond reasonably well and are straightforward to inject.
Intra-articular PRP for hip osteoarthritis has thinner evidence than the knee, partly because the hip joint is deep and requires imaging guidance for accurate placement.
PRP for plantar fasciitis, foot pain, and ankle pain
PRP for plantar fasciitis is one of the better-supported uses in the foot. Chronic plantar fasciopathy that has failed orthotics and night splints for six months or more is a reasonable candidate, and it is one of the few foot conditions where PRP has been tested head to head against corticosteroid injection in randomized trials.
PRP for foot pain also covers Achilles insertional tendinopathy and posterior tibial tendon problems, though results there are mixed. PRP for ankle pain includes post-traumatic ankle arthritis and chronic peroneal tendinopathy.
PRP for sports injuries
Hamstring strains and patellar tendinopathy are the common uses in athletes. Speed of return to play has not consistently improved in controlled trials for acute muscle strains.
PRP is legal in competition, since the World Anti-Doping Agency removed it from the prohibited list in 2011. For chronic tendinopathy in a competing athlete, PRP offers something cortisone does not, which is treatment that avoids weakening the tendon.
How effective is PRP therapy
PRP is a real treatment with moderate effect sizes and a lot of variability between patients. That variability comes from four things: the preparation system, injection accuracy, the severity of the underlying damage, and what the patient does afterward. Two people with the same diagnosis can get very different results from what gets marketed as the same procedure.
PRP is not a cure for arthritis. It does not regrow cartilage in a worn joint. What the evidence supports is pain reduction and functional improvement lasting somewhere between six and eighteen months, after which many patients repeat the injection.
For someone trying to delay a knee replacement by a few years, that is a reasonable trade. For someone expecting a new knee, it is not.
PRP therapy benefits and what recovery looks like
The main benefits are that PRP regenerative therapy uses autologous material, so allergic reaction and rejection are not concerns, and that it avoids the tendon weakening and cartilage effects associated with repeated corticosteroid injections. Infection risk is very low.
The most common side effect is a flare of soreness and swelling at the injection site lasting two to five days, which is the inflammatory response doing its job.
You stop anti-inflammatory medication for about a week before and two weeks after, since NSAIDs blunt the platelet activity the treatment depends on.
Most protocols call for relative rest for a few days, then a graded return to loading. PRP therapy for joint pain and PRP therapy for chronic pain both work considerably better when paired with rehab.
The injection creates a repair window. Loading the tissue correctly during that window is what turns it into durable improvement.
PRP therapy cost
PRP injections in the United States generally run 2,500 per session, with about $1,000 being typical. Knee and hip injections sit toward the higher end, elbow and foot toward the lower.
Most treatment plans involve one to three injections spaced three to four weeks apart.
Insurance almost never covers it. Nearly all private payers and Medicare classify PRP for musculoskeletal conditions as investigational, so it is an out-of-pocket expense.
Workers' compensation and some auto injury claims are occasional exceptions depending on your state. HSA and FSA funds usually can be applied. Get the total plan cost in writing before the first injection, including imaging guidance and follow-up visits, because quoted prices are often per injection rather than per course.
PRP therapy myths
Three claims come up repeatedly and none of them hold.
PRP does not use stem cells. Platelets are cell fragments without nuclei, and clinics that market PRP as stem cell therapy are either confused or being deliberately vague.
PRP does not rebuild cartilage. Imaging studies have shown slowed or halted progression in treated knees, which is a different claim from new cartilage growing back. The improvement patients feel comes from a calmer joint environment and better tendon quality.
PRP is not experimental in the sense of being untested. It has been studied in hundreds of randomized trials since the mid-2000s. The investigational label insurers apply is a coverage decision about consistency of benefit, and it is not a statement that the treatment lacks evidence.
Choosing a PRP therapy specialist
Ask four questions. What platelet concentration does your system produce, and is it leukocyte-rich or leukocyte-poor? Do you use ultrasound guidance for this injection? How many of these have you done for my specific diagnosis? What does the rehab protocol after the injection look like?
A provider who cannot answer the first question is running blind on the variable that the 2025 evidence identifies as the strongest predictor of results. A provider who injects a shoulder or hip by feel alone is guessing at placement in a joint where guidance measurably improves accuracy. Orthopedic PRP therapy delivered well is a legitimate option for the right patient. Delivered casually, it is an expensive placebo.
Frequently asked questions
How long does it take for PRP therapy to start working?
Most patients notice nothing for the first two to four weeks, and many feel worse for the first three to five days because of the deliberate inflammatory response. Improvement typically builds through month three and peaks around month six. If you have felt no change at all by twelve weeks, the treatment probably did not take. Raise that with your provider before scheduling another round.
Is a PRP injection painful?
The blood draw is routine. The injection itself varies by location. Intra-articular knee injections are usually well tolerated with local anesthetic. Tendon injections, particularly the plantar fascia and the common extensor origin at the elbow, are more uncomfortable because the needle passes through dense tissue and the tendon is often fenestrated during the procedure. The soreness afterward is generally rated moderate and settles within a week. Ice and acetaminophen are fine. Ibuprofen and naproxen are not, since they interfere with the platelet signaling.
How many PRP injections will I need?
Most protocols use one to three injections spaced three to four weeks apart, and the number depends on the diagnosis. Knee osteoarthritis studies frequently use a three-injection series. Lateral epicondylitis and plantar fasciitis often respond to a single injection. Benefits typically last six to eighteen months, and repeat treatment is common at that point rather than being a sign the first round failed.
Who is not a good candidate for PRP therapy?
People with active infection, blood cancers, low platelet counts, or significant anemia should not receive PRP. Patients on anticoagulants need a plan worked out with the prescribing physician. Grade 4 bone-on-bone arthritis rarely responds well enough to justify the cost. Anyone who cannot pause NSAIDs for about three weeks around the procedure will get less out of it. Smoking meaningfully impairs the healing response PRP depends on.
Does PRP therapy work better than cortisone?
It depends on your time horizon. Cortisone wins in the first month for most conditions because it suppresses inflammation immediately. PRP catches up around month three and holds its advantage at six and twelve months in knee osteoarthritis and lateral epicondylitis, which is the pattern in the meta-analyses cited above. Cortisone also carries a cost with repeat use, including tendon weakening and cartilage effects that limit how many injections a joint should receive. If you need relief for an event next week, cortisone is the better tool. If you are trying to change the trajectory of a chronic problem, PRP is the better bet. Talk to an orthopedic provider who does these regularly and will tell you honestly whether your specific injury falls into the group that responds. The right answer for a grade 2 knee with six months of failed therapy is different from the answer for a full-thickness rotator cuff tear, and a good specialist will say so.
