PRP for Knee Osteoarthritis in Los Angeles

Start here

What is a PRP knee injection?

PRP is made by drawing blood, concentrating platelets in a smaller volume of plasma, and injecting the prepared product into the knee. It is not a stem-cell treatment, and the letters “PRP” do not tell you the dose or full composition.

01

Start with the diagnosis

PRP should be considered only after the knee problem and meaningful functional goals are reasonably clear.

02

Expect symptom treatment

The realistic goals are less pain and better function. PRP has not been proven to regrow cartilage or prevent knee replacement.

03

Characterize the product

Platelet dose, injected volume, leukocytes, red blood cells, preparation, and schedule can vary substantially.

04

Keep rehabilitation central

PRP is an optional part of a broader plan, not a substitute for progressive exercise and activity planning.

After a knee osteoarthritis diagnosis, start with the beginner exercise program or use the advanced progression when appropriate. These are foundational guides, not a universal post-PRP protocol.

FDA status matters.

FDA has not approved a PRP drug or biologic for treating knee osteoarthritis. Some devices are cleared for preparing or handling autologous PRP, sometimes for a narrower stated use. Device clearance does not mean FDA has determined that PRP is effective for knee osteoarthritis.21

Start with the complete knee osteoarthritis treatment guide

Could PRP fit?

A focused discussion may be reasonable when four things are true.

Symptoms persist despite an appropriate exercise and rehabilitation plan.
The diagnosis is reasonably clear.
The goal is better pain and function, not cartilage regrowth.
You want to compare PRP with other options, including cost and uncertainty.

Financial and professional transparency: Dr. Swisher evaluates and treats patients considering PRP when clinically appropriate. PRP may involve out-of-pocket cost. UCLA Health manages current availability, pricing, coverage, scheduling, and clinical communication.

Current evidence

Does PRP work for knee osteoarthritis?

A 2025 meta-analysis of 18 placebo-controlled trials involving 1,995 patients found clinically meaningful WOMAC improvement across follow-up, with pain improvement most evident at three and six months. In a subgroup analysis split at roughly one million platelets per microliter, the higher-concentration trials accounted for the durable pain benefit. That analysis compared concentration, not total platelets delivered.1

A separate 2025 placebo-controlled meta-analysis of 11 trials and 1,616 patients found pain improvement at three and six months and WOMAC improvement at three months, but no significant benefit at 12 months and substantial heterogeneity. Conclusions depend partly on which trials, PRP products, outcomes, and time points are included.2

These pooled results do not erase important negative trials. In the 288-patient RESTORE trial, three weekly leukocyte-poor PRP injections did not improve 12-month pain or medial tibial cartilage volume compared with saline. Twenty-nine of 31 prespecified secondary outcomes also showed no difference between groups.3

One large multicenter sham-controlled trial reported sustained symptom benefit and slower cartilage volume loss than saline over five years. Its effect size and structural finding sit at the outer edge of the positive evidence and have not been consistently reproduced.4 Taken together, the evidence suggests that some PRP protocols help some patients, but we still cannot reliably predict which preparation or patient will respond.

What pooled studies show

Across many trials, average pain and function outcomes generally favor PRP over placebo or common comparators.

What negative trials show

Several well-designed saline-controlled studies have found little or no benefit, including RESTORE.

Clinical meaning

A favorable average does not predict an individual response, and the preparation used in one study may not match another.

Why apparently similar trials can disagree

Studies vary in platelet dose, injected volume, leukocytes and neutrophils, red blood cell contamination, activation, number and timing of injections, image guidance, rehabilitation, osteoarthritis severity, and outcome measurement.

Product characterization

PRP is a dose, not just a label.

A statement such as “four times concentrated” is incomplete unless the starting count, final concentration, and injected volume are known. Total deliverable platelets provide a more useful description of what reaches the knee.

Total platelet dose

Final platelets per microliter × injected volume in milliliters × 1,000 = total deliverable platelets.

For example, 1.25 million platelets per microliter in 8 mL yields 10 billion total platelets.

Core dose

Final platelet concentration, injected volume, and calculated total deliverable platelets.

Cell composition

Leukocytes, neutrophils, and red blood cell contamination can distinguish biologically different products.

Protocol

Preparation method, activation, device settings, injection number, guidance, and rehabilitation plan.

Why total platelet delivery deserves attention

01
Concentration signal
The 2025 Bensa meta-analysis found greater clinical improvement in higher-concentration PRP groups, although concentration is not the same as total dose.1
02
Direct randomized signal
A 2024 triple-blind trial in early knee osteoarthritis reported better three- and six-month outcomes with about 5.65 billion platelets in 8 mL than with about 2.82 billion in 4 mL. Dose and volume changed together, so the trial does not isolate platelet dose alone. Neither arm reached 10 billion.5
03
Where the 10-billion signal began
A single-center randomized study in 150 patients compared a filtered preparation delivering about 10 billion platelets with hyaluronic acid and reported better 12-month outcomes. It was not a dose-comparison trial and did not establish a minimum effective dose or reproducible structural benefit.6
04
A total-dose subgroup analysis
A 2026 meta-analysis grouped PRP arms from 32 randomized trials by total deliverable platelet dose: 1 to 5 billion, 5 to 10 billion, or more than 10 billion. All three groups improved outcomes compared with hyaluronic acid, and the 5 to 10 billion group had the largest pooled effect. These were indirect across-trial subgroup comparisons, not randomized head-to-head dose comparisons, so the analysis shows association rather than an optimal dose.7
05
Current best-practice guidance
The 2026 AAPM&R clinical guidance separately identifies at least 10 billion total deliverable platelets as a consensus-based best-practice target for knee osteoarthritis.8

Evidence is not one-directional. A separate 2025 meta-analysis grouped trials by platelet fold-increase and found larger effects with lower or moderate concentration ranges than with higher ranges. Fold concentration and total deliverable dose are different measures, and neither study design establishes an optimal universal dose.9

Bottom line

Total platelet delivery may matter. The optimal dose and range are not settled.

Current AAPM&R guidance names at least 10 billion total deliverable platelets as a consensus-based best-practice target. The 2026 meta-analysis that sorted trials by total dose found the largest effect in the 5 to 10 billion range, not above it. Treat 10 billion as a reference point for describing and comparing products, not as a proven biological threshold, a guarantee, or evidence that more is always better.

Questions worth asking about any PRP product

What is being delivered? Ask for final platelet concentration, injected volume, and total platelet dose.
What else is in it? Ask whether the clinician measures or otherwise characterizes leukocytes, neutrophils, and red blood cells.
Why this schedule? Ask why one injection or a series is being recommended for this diagnosis.
How will it be judged? Define the functional goal, reassessment timing, rehabilitation plan, and total cost.

This page explains how to evaluate any PRP product. It does not describe the specific product or protocol that would be used for an individual visit. Product details should be reviewed in clinic before anything is scheduled.

Patient selection

Who is a candidate for a PRP knee injection?

PRP is generally considered after the diagnosis is clear and foundational treatment has not provided enough relief. The decision should start with the knee and your goals, not with the availability of an injection.

Best supported by evidence

Persistent symptomatic mild-to-moderate knee osteoarthritis after an appropriate exercise, rehabilitation, and symptom-management plan.

Realistic treatment goal

Improve pain and function enough to support meaningful activity, while understanding that nonresponse is possible.

Lower confidence or defer

End-stage disease, active infection, major diagnostic uncertainty, or expectations of cartilage regrowth. A new hot, markedly swollen, painful knee needs same-day medical assessment because joint infection cannot be excluded by symptoms alone, even without fever. Do not wait for a routine injection visit.

The evidence summarized here comes from osteoarthritis trials. It does not establish benefit for rheumatoid or other inflammatory arthritis, gout or another crystal arthritis, infection, or an unrecognized structural injury. If the diagnosis is not settled, the first visit should focus on clarifying it rather than planning PRP.

Age, disease severity, alignment, metabolic health, medications, prior treatment, and activity demands may influence the discussion. No single test reliably predicts who will benefit.

Considering PRP?

Schedule a knee osteoarthritis consultation with Dr. Swisher.

Call UCLA Orthopedics and ask for Jeremy Swisher, MD in Westwood or West Hills. Mention that you want to discuss whether PRP fits your diagnosis and goals.

Call 310-319-1234

Before, during, and after

What to know before and after a PRP knee injection.

PRP instructions vary because products and study protocols vary. The written instructions from the clinician performing the procedure should take precedence, especially when another clinician prescribes an essential medicine.

Never stop a prescription medicine on your own

Do not stop aspirin, an anticoagulant, an antiplatelet medicine, corticosteroid, antibiotic, prescription omega-3, or any other prescribed treatment without coordination between the clinician performing PRP and the clinician who prescribed it. If an essential medicine cannot be interrupted safely, postponing an elective PRP procedure may be safer than interrupting treatment.

Before your PRP injection

Confirm the diagnosis and target
Review the history, examination, and appropriate imaging. A new hot, markedly swollen, painful knee needs same-day medical assessment because joint infection cannot be excluded by symptoms alone, even without fever. Do not wait for a routine injection visit. Active infection or major diagnostic uncertainty should also be addressed before an elective injection.
Send a complete medication list
Include every prescription, over-the-counter medicine, topical pain product, vitamin, and supplement, with the dose and reason for use. Report recent cortisone injections and all steroid use.
Share medical conditions that may change timing
Active cancer, a tumor near the injection site, significant blood-count abnormalities, dialysis, long-term antibiotics, or immunosuppression require individualized specialist coordination. Formal 2025 expert consensus generally advises postponing elective PRP during evaluation or treatment of active cancer and avoiding injection near a tumor. Most of these recommendations come from expert consensus rather than randomized trials.10
Also tell the clinic if you are pregnant, planning pregnancy, or breastfeeding so the timing and alternatives for an elective procedure can be reviewed individually with the clinicians involved in your care.
Call if health changes
PRP should be deferred for active bacterial infection or an infected or open skin site near the knee. Contact the clinic for fever, chills, antibiotic treatment, a dental infection, or recent invasive dental work. Formal expert consensus advises waiting until a short antibiotic course is finished and the infection has resolved, and until dental treatment has healed. A chronic infection requiring long-term antibiotics needs infectious-disease coordination. Never stop an antibiotic early.10
Prepare for the blood draw
Unless told otherwise, do not fast. Eat a normal light meal and drink water. Avoiding a high-fat meal for 24 hours and alcohol for 48 hours is a low-certainty consensus recommendation, not a proven outcome requirement.22

Medication and supplement review

Know what to discuss, and what not to stop.

Nonsteroidal anti-inflammatory drugs (NSAIDs). Nonselective NSAIDs such as ibuprofen, naproxen, and diclofenac can inhibit platelet function. COX-2 selective NSAIDs have substantially less platelet effect. Whether either group changes clinical PRP outcomes is unproven, so follow the written medicine-specific plan and ask about topical NSAIDs too.
Aspirin and antiplatelet medicines. Avoid starting aspirin for pain unless instructed. If aspirin, clopidogrel, or another antiplatelet was prescribed for your heart, brain, blood vessels, or a stent, do not stop it. The prescribing and PRP clinicians must coordinate.
Anticoagulants or blood thinners. Report warfarin, apixaban, rivaroxaban, dabigatran, edoxaban, enoxaparin, and similar medicines. Joint injection is generally a low-bleeding-risk procedure, but individual risk and PRP candidacy still require review.24
Acetaminophen. Acetaminophen is not an NSAID and is commonly used when medically safe, but laboratory studies of platelet aggregation have produced conflicting results and no clinical trial shows that it changes PRP outcomes. Use only the dose approved by the treating clinician, especially with liver disease, heavy alcohol use, or combination products.11
Corticosteroids and antibiotics. Report recent cortisone injections and oral, injected, inhaled, or topical steroid use. A recent injection into the target joint may change timing. Never stop chronic steroids suddenly. Active bacterial infection should resolve and a short antibiotic course should be complete before elective PRP, based on formal expert consensus.
Supplements. Report concentrated garlic, turmeric or curcumin, ginkgo, high-dose vitamin E, fish oil or omega-3, and other supplements. Evidence about bleeding risk differs by supplement and clinical setting. A broad clinical review did not associate fish oil with bleeding, while evidence for several other supplements was limited or context dependent. No supplement-specific PRP outcome evidence establishes a standard hold.26

What is known about timing?

Some expert consensus protocols use a cautious period off NSAIDs before and after PRP. Pharmacology studies show that platelet inhibition varies substantially by medicine, and no human outcome trial proves that one period off medication improves PRP results. One systematic review reported reduced platelet aggregation with acetaminophen in a small number of patients and suggested considering a hold.11 A later pharmacologic review classified it as not requiring deferral.16 Neither review measured PRP outcomes. The individualized written plan is more important than a universal number.

The infection, dental procedure, cancer, and dialysis recommendations above come from a formal 2025 expert consensus. Most are based on lower-certainty evidence rather than randomized trials.

What to expect during the procedure

Blood is drawn and processed, the skin is cleaned, and the prepared PRP is injected. Ultrasound guidance may be used to visualize the knee and needle. The visit may take longer than the injection itself because product preparation requires time.

PRP is generally well tolerated, but it is not risk-free.

A 2025 meta-analysis of 24 randomized trials involving 2,751 patients reported adverse events or complications in 18.7% of PRP recipients and 9.1% across pooled comparator injections. The authors calculated a number needed to harm of 11 across that mixed comparator pool. Rates did not differ statistically from hyaluronic acid or corticosteroid and were higher than saline. One patient reported severe pain; the remaining events were described as mild or moderate and self-limiting, most often transient pain or swelling.12

A separate 2026 safety meta-analysis found that mild knee pain and swelling were the most common events. Leukocyte-rich PRP accounted for most of the difference compared with hyaluronic acid, while leukocyte-poor PRP was not significantly different. No severe adverse events were observed in that trial pool.13 Rare serious injection complications, including joint infection, remain possible. Other risks include bruising or bleeding, lightheadedness or fainting, injury to nearby structures, and no meaningful benefit.

After your PRP injection

Use relative rest for the first 24 hours
Normal necessary walking is usually reasonable as tolerated, but avoid strenuous exercise and heavy loading. Do not remain completely inactive unless the care team gives a specific reason.
Expect a possible temporary flare
Soreness, stiffness, or swelling can occur and may feel worse before it feels better. It often begins improving over the next several days, although duration varies.
Follow the provided pain plan
Follow the medicine-specific pain plan provided by your clinician. Published study protocols vary widely. Fewer than half specified a post-injection NSAID restriction; seven days was the most frequent single duration, but no clinical trial establishes that a particular medication window improves PRP outcomes.25 Acetaminophen may be used when approved and medically safe.
Resume loading gradually
No single post-PRP knee program has been validated. Restore motion, walking, strength, and higher-demand activity in stages. Tendon and ligament PRP require different loading schedules.25

Bandage and water

Keep the puncture site clean and follow the bandage and shower instructions you received. Avoid soaking until the puncture has closed.

Cooling and heat

Brief use of a cold pack may ease discomfort, but whether ice changes PRP biology or outcomes is unknown. Avoid extreme heat or soaking the puncture site until the skin has closed.

Driving

Do not drive after a sedating medicine, lightheadedness, temporary numbness, or if you cannot steer and brake firmly without hesitation. Arrange a ride if there is any doubt.

Evidence versus clinic protocol

Temporary flare, relative rest without immobilization, medication review, and postponing elective PRP during active infection have broad support. Exact NSAID windows, recent steroid timing, alcohol and diet guidance, ice, bandage, shower, driving, and rehabilitation details rely more heavily on consensus or local protocol.

One injection or a series?

Some meta-analyses of small randomized trials favor three injections over one for pain or function, but studies differ in platelet dose, product, spacing, and risk of bias. RESTORE also used three injections and found no benefit over saline. No universally validated schedule exists, and a series should not be presented as automatically necessary or superior for every patient.14

When to seek urgent care after an injection

Seek same-day urgent medical assessment and contact the injecting team for fever or chills, drainage, spreading redness or warmth, rapidly increasing swelling, new one-sided calf swelling, pain that is severe or progressively worsening rather than settling, significant bleeding, new weakness or numbness, or inability to bear weight. Do not wait for a routine reply. Call 911 for trouble breathing, fainting, chest pain, confusion, severe illness, or another medical emergency.

Guideline context

PRP guidelines for knee osteoarthritis.

Professional groups review different evidence, use different thresholds for clinical importance, and publish at different times. These include physical medicine and rehabilitation, orthopaedic surgery, federal health systems, and a European sports medicine and cartilage consensus group. The date and scope of a recommendation matter.

AAPM&R, 2026

This guidance contains five evidence-based clinical recommendations and 11 consensus-based best practices. It supports considering PRP after failed conservative care in mild-to-moderate knee osteoarthritis and identifies at least 10 billion total deliverable platelets as a consensus-based best-practice target.

AAOS, 2021

States that PRP may reduce pain and improve function, but rates the recommendation as limited.

VA/DoD, 2026

Finds insufficient evidence to recommend for or against PRP because the research remains heterogeneous and very uncertain.

ESSKA-ICRS, 2024

Supports selected use after conservative care has failed in patients age 80 or younger with Kellgren-Lawrence (KL) grade 0 to 3 disease, but not as first treatment or for KL grade 4.20

ESSKA-ORBIT, 2024

Regards PRP as a valid option, mainly for KL grade 1 to 3 knee osteoarthritis, while noting that many product and protocol recommendations rely on medium-to-low quality evidence or expert opinion.22

ACR/AF, 2019

Strongly recommends against PRP for knee and hip osteoarthritis because preparations and techniques were heterogeneous and not standardized. Its evidence review predates the newer dose-focused trials and 2026 AAPM&R guidance.

Guidelines inform the conversation. They do not replace individual diagnosis, medical screening, cost discussion, and shared decision-making. A separate AMSSM position statement emphasizes responsible use of orthobiologics, including transparent communication about evidence, risks, alternatives, and regulatory status.15

Cost and alternatives

PRP cost, insurance, and alternatives.

PRP is often not covered by insurance and may involve substantial out-of-pocket cost. Coverage, authorization, product availability, and pricing should be confirmed with the clinic and health plan before treatment. Ask for a current written estimate and whether it includes the evaluation, PRP preparation kit, procedure, ultrasound guidance if used, and any later injection or follow-up visit.

Foundational care. Education, progressive exercise, rehabilitation, activity planning, and weight-management support when relevant.
Medication options. Topical or oral medicines when appropriate for your health history.
Other injections. Corticosteroid or hyaluronic acid may be discussed selectively, with different evidence, timing, risks, and coverage.
Surgical consultation. Appropriate when substantial symptoms and limitations persist or advanced disease changes the balance of options.

Compare PRP, hyaluronic acid, and corticosteroid injections

Read the detailed hyaluronic acid guide

PRP transparency: Dr. Swisher evaluates and treats patients considering PRP when clinically appropriate. PRP may involve out-of-pocket cost. This educational page does not replace procedure-specific informed consent or a cost discussion with UCLA Health.

UCLA Health locations

Where to discuss PRP in Los Angeles.

An evaluation is available at either clinic. Call 310-319-1234 and ask to schedule with Jeremy Swisher, MD. Mention the location you prefer and that you want to discuss PRP.

Westwood

Westwood Orthopedics & Sports Medicine
100 UCLA Medical Plaza, Suite 170
Los Angeles, CA 90095

West Hills

West Hills Orthopedic Surgery
7230 Medical Center Drive, Suite 604
West Hills, CA 91307

Compare clinics, directions, and parking information

Common questions

PRP for knee arthritis FAQs

Does PRP work for knee osteoarthritis?

PRP may improve pain and function for some people with knee osteoarthritis, but placebo-controlled trials and guidelines conflict. It does not reliably regrow cartilage or guarantee that an individual patient will improve.

Who is a candidate for a PRP knee injection?

The evidence is most aligned with selected patients who have persistent symptomatic mild-to-moderate knee osteoarthritis after an appropriate exercise and rehabilitation plan, a reasonably clear diagnosis, and realistic goals of improving pain and function rather than regrowing cartilage.

Is PRP proven to regrow knee cartilage?

No. PRP is used with the goal of improving symptoms and function. Current evidence does not establish reliable cartilage regeneration, reversal of osteoarthritis, or avoidance of future knee replacement.

Does a 10-billion platelet dose guarantee success?

No. The 2026 AAPM&R guidance identifies at least 10 billion total deliverable platelets as a consensus-based best-practice target. A separate 2026 meta-analysis grouped PRP arms from 32 randomized trials by dose. The 5 to 10 billion group had the largest pooled effect compared with hyaluronic acid, but patients were not randomized between dose categories. This indirect comparison does not establish a universal threshold or predict an individual response.

Is leukocyte-poor or leukocyte-rich PRP better?

Current evidence does not establish that leukocyte-poor PRP provides better symptom relief than leukocyte-rich PRP. A 2024 head-to-head randomized trial found similar one-year outcomes and adverse events. A 2026 safety meta-analysis found more transient pain and swelling with leukocyte-rich PRP than with hyaluronic acid, while leukocyte-poor PRP was similar to hyaluronic acid. Leukocyte content should be reported, but it is only one part of the product.

How many PRP injections are needed for knee osteoarthritis?

There is no universally validated schedule. Some analyses of small trials favor three injections over one for certain outcomes, but products, dose, spacing, study quality, burden, and cost differ. A series is not automatically necessary or superior for every patient.

How quickly does PRP work?

When benefit occurs, it is usually assessed over weeks to months rather than immediately. Temporary soreness in the first several days is common. The timing and degree of improvement vary.

How long can PRP relief last?

Benefit is most consistently seen over the first three to six months in pooled placebo-controlled evidence. Some studies report improvement at 12 months or longer, but those findings are less consistent and do not predict how long an individual response will last.

Do I need to stop ibuprofen, aspirin, or a blood thinner before PRP?

Do not stop a prescribed medicine on your own. Nonselective NSAIDs can inhibit platelet function, but no clinical trial establishes one universal medication window. Aspirin, antiplatelet medicines, and anticoagulants require coordination between the prescribing clinician and the clinician performing PRP.

Which supplements should I report?

Report every vitamin and supplement, especially concentrated garlic, turmeric or curcumin, ginkgo, high-dose vitamin E, and fish oil or omega-3. Bleeding evidence differs among products, and there is no supplement-specific PRP evidence establishing a standard hold. Do not stop a prescription omega-3 or medically indicated supplement without the prescriber's approval.

What can I take for pain afterward?

Acetaminophen is not an NSAID and is commonly used when medically safe, but laboratory platelet studies conflict and no clinical trial shows that it changes PRP outcomes. Use only the dose approved by the treating clinician, especially with liver disease, heavy alcohol use, or combination medicines containing acetaminophen.

When can I exercise after a PRP knee injection?

Use relative rest for the first 24 hours unless instructed otherwise, then resume motion and loading gradually. There is no single validated knee aftercare program. Follow the indication-specific written plan and coordinate progression with your physical therapist when applicable.

How much does PRP cost at UCLA Health?

This independent website does not quote UCLA Health pricing. PRP may involve out-of-pocket cost. Ask UCLA Health for the current estimate and what it includes before scheduling a procedure.

Does insurance cover PRP for knee osteoarthritis?

PRP is often not covered for knee osteoarthritis, but plan rules differ. Confirm benefits, authorization requirements, and your expected out-of-pocket responsibility directly with UCLA Health and your health plan.

Is PRP worth it for knee osteoarthritis?

That depends on diagnostic confidence, symptom severity, prior rehabilitation, goals, treatment alternatives, uncertainty, risk, and cost. A consultation should clarify those tradeoffs without assuming that an injection is the right next step.

What if PRP does not help?

Reassess the diagnosis, other contributors to pain, rehabilitation dose, activity plan, and the functional goal. Repeating PRP is not automatic. Depending on the findings, reasonable next steps may include adjusting rehabilitation, medication or bracing, discussing a different injection, or considering a surgical opinion.

Where can I see Dr. Swisher to discuss PRP in Los Angeles?

Dr. Swisher evaluates patients at UCLA Health locations in Westwood and West Hills. Call 310-319-1234 and ask to schedule a knee osteoarthritis consultation with Jeremy Swisher, MD. Mention that you want to discuss PRP.

Can I schedule PRP directly?

Call UCLA Orthopedics to arrange an evaluation with Dr. Swisher. Candidacy, product availability, cost, medication instructions, and procedure timing must be reviewed first, so an injection is not guaranteed at the initial visit.

Evidence

Sources and further reading

These sources include supportive and negative evidence so patients and clinicians can see why shared decision-making remains essential.

View all 29 evidence sources

Evidence and recommendations can change. This page is educational and does not establish whether PRP is appropriate for a particular patient.

PRP knee injections in Los Angeles.

Which guide should I read?