Were You Told PRP Didn't Work, or That All PRP Is the Same? It Isn't.
Platelet-rich plasma therapy has become one of the most sought-after treatments in orthopedic medicine — and one of the most misunderstood. Patients who had disappointing results with PRP elsewhere are often surprised to learn that the quality, concentration, and composition of PRP varies enormously from one physician's office to another. The system used, the volume of blood drawn, the method of processing, and the ability to customize the final product all determine whether PRP will be effective for your specific condition.
At Dr. Mirzayan's practice, PRP is not a commodity procedure. It is a precision treatment — prepared with advanced technology and administered with the same level of care and expertise that defines every procedure he performs.
What Is PRP and How Does It Work?
Your blood contains plasma, red blood cells, white blood cells, and platelets. Platelets are small cells best known for their role in clotting, but they are also rich in growth factors — proteins that signal the body to initiate and accelerate tissue repair. When platelets are concentrated and delivered directly to a site of injury or degeneration, they can stimulate healing in tissue that has limited natural blood supply and poor healing capacity on its own, such as tendons, ligaments, and cartilage.
Platelet-rich plasma is created by drawing your blood, spinning it to concentrate the platelets, and injecting that concentrated product back into the treatment site. The critical variable — the one that most patients and even many physicians overlook — is what happens between the blood draw and the injection.
Not All PRP Is the Same — And the Difference Matters
PRP is not regulated by the FDA as a standardized drug or biologic product. There is no requirement that a physician use any particular system, draw any minimum volume of blood, or achieve any specific platelet concentration or count. This means the PRP being administered in one office may be dramatically different — in platelet count, concentration, volume, and composition — from what is being administered in another. Even two blood draws from the same patient on the same day can yield different products.
When evaluating PRP, these are the questions every patient should ask:
- Which system does the physician use, and how does it process the blood?
- How many cc's of blood are drawn?
- What platelet concentration and total platelet count does the system achieve?
- Can the system produce both leukocyte-rich and leukocyte-poor formulations?
- If multiple sites need to be treated, is there a separate fee for each one?
These questions matter because the answers determine whether your PRP treatment has a meaningful chance of working, and they affect what you will pay.
The Arthrex Angel System
Dr. Mirzayan uses the Arthrex Angel system, one of the most sophisticated PRP platforms available. Most PRP systems draw 8cc to 30 cc of blood and rely on a single centrifuge spin to separate blood components. The Angel system works differently.
The Angel system begins with a centrifuge separation, then passes the separated blood past an optical sensor that detects in real time when plasma, platelets and white blood cells, and red blood cells are passing through. The system diverts each layer into the correct compartment, producing a PRP product that is both highly concentrated and customizable.
The Angel system can achieve platelet concentrations up to 18 times a patient's own baseline, and lets Dr. Mirzayan control the final composition of the PRP — including whether the product is leukocyte-rich or leukocyte-poor, depending on what your condition requires.
This distinction has clinical support. For tendon conditions such as tennis elbow, the largest randomized trial to date used leukocyte-rich PRP and found meaningful improvement at 24 weeks (Mishra et al., American Journal of Sports Medicine, 2014). For injection inside a joint, such as knee arthritis, leukocyte-poor formulations have been associated with better outcomes and fewer adverse reactions (Riboh et al., American Journal of Sports Medicine, 2016). A PRP system that cannot produce both formulations cannot be matched to every patient and every condition.
The Angel system costs more to operate than standard PRP platforms. Dr. Mirzayan uses it because it produces a more consistent and customizable product.
Disclosure: Dr. Mirzayan is a paid consultant and educator for Arthrex, the manufacturer of the Angel system. He selected this system for his practice on clinical grounds, and discloses this relationship so patients can weigh it for themselves.
Why Total Platelet Dose Matters More Than Concentration
When PRP first gained popularity, marketing from device companies focused heavily on concentration — how many times above baseline the platelets were. A decade of research has shifted that framing. What appears to matter more is the total number of platelets delivered to the treatment site, not just how concentrated they are relative to baseline.
The strongest evidence for this comes from a randomized trial in knee osteoarthritis that delivered a dose of 10 billion platelets and reported sustained improvement in pain and function at one year compared with hyaluronic acid (Bansal et al., Scientific Reports, 2021). That trial established a dose that worked; it did not establish an absolute minimum, and research on the optimal dose is ongoing. Reaching a dose in that range generally requires drawing substantially more blood than the 8cc – 30 cc most standard PRP systems are designed to handle.
This also helps explain one of the most-cited negative studies in the field. The RESTORE trial, published in JAMA, found that PRP was no better than saline for knee osteoarthritis (Bennell et al., JAMA, 2021). That trial used a low-volume preparation delivering a fraction of the platelet dose used in the Bansal trial. Dr. Mirzayan believes dose is a large part of why results across PRP studies have been so inconsistent — but this remains an area of genuine scientific debate, and he will tell you that directly rather than overstate what the evidence shows.
Dr. Mirzayan draws the volume of blood necessary to achieve a clinically meaningful platelet count for your specific condition. This is not the approach taken at most PRP clinics.
How to Prepare for Your PRP Treatment
How you prepare your body before the blood draw affects the quality of your PRP. Dr. Mirzayan recommends the following in the days leading up to your procedure:
- Eat well. Good nutrition in the days before your draw supports platelet production. Do not fast before your appointment. A high protein diet is recommended.
- Stay hydrated. Arrive well hydrated. Dehydration affects blood volume and platelet yield.
- Avoid alcohol and tobacco for at least several days before your procedure, as both impair platelet function.
- Stop anti-inflammatory medications (NSAIDs such as ibuprofen and naproxen) for at least one week before your appointment, as these interfere with platelet activity.
- Exercise vigorously for 10–15 minutes immediately before your blood draw. Short-duration vigorous exercise transiently increases circulating platelet counts. If possible, arrive a few minutes early and take a brisk walk or do jumping jacks before coming in.
- Start taking Tylenol 1000mg 1 hour before your appointment.... unless you have been advised not to take acetaminophen. Unlike ibuprofen and naproxen, acetaminophen does not interfere with platelet function, so it is safe to use around your PRP treatment. Dr. Mirzayan does not mix local anesthetic into the PRP, because laboratory studies suggest local anesthetics can impair platelet function. This means the injection itself is more uncomfortable than a typical cortisone shot.
These steps are part of optimizing your treatment, not optional extras. Have questions about what to expect? Call our office at (310) 746-5918 and we will walk you through everything.
Conditions Treated with PRP
Dr. Mirzayan uses PRP for orthopedic conditions where biologic stimulation of healing is appropriate. The quality of evidence differs by condition, and it is listed honestly below.
Tennis elbow (lateral epicondylitis)
One of the best-supported uses of PRP. In a multicenter randomized controlled trial of 230 patients with chronic tennis elbow, leukocyte-rich PRP produced significantly greater improvement in pain and tenderness than an active control at 24 weeks (Mishra et al., American Journal of Sports Medicine, 2014). Notably, the difference did not appear at 12 weeks — PRP for tendinopathy requires patience.
Golfer's elbow (medial epicondylitis)
Treated with the same leukocyte-rich approach used for tennis elbow. The published evidence base for medial epicondylitis is considerably smaller than for lateral epicondylitis, and much of the rationale is extrapolated from the lateral side. Dr. Mirzayan will discuss this distinction with you.
Partial UCL tears in throwing athletes
For throwers with partial ulnar collateral ligament tears hoping to avoid Tommy John surgery, PRP has a meaningful track record. A prospective series of 34 athletes with partial UCL tears reported successful return to play after PRP (Podesta et al., American Journal of Sports Medicine, 2013), and a review of 44 high-level throwers reported good or excellent outcomes in the majority (Dines et al., American Journal of Orthopedics, 2016).
Equally important is where PRP does not work: a cohort study analyzing outcomes by injury grade found PRP beneficial for lower-grade partial tears but not appropriate for complete UCL tears (Mills et al., Orthopaedic Journal of Sports Medicine, 2021). Dr. Mirzayan grades your tear on MRI before recommending PRP, and will tell you if reconstruction is the better answer.
Knee osteoarthritis
One of the most-studied applications of PRP, and also one of the most debated. Meta-analysis of randomized trials has found PRP superior to hyaluronic acid for pain and function in knee osteoarthritis (Belk et al., American Journal of Sports Medicine, 2021), and a properly dosed randomized trial showed benefit sustained to one year (Bansal et al., Scientific Reports, 2021). Other high-quality trials have been negative (Bennell et al., JAMA, 2021). Leukocyte-poor PRP is generally preferred for injection into a joint (Riboh et al., American Journal of Sports Medicine, 2016). PRP is most appropriate for mild to moderate arthritis; it will not regrow cartilage in an end-stage knee.
Partial-thickness rotator cuff tears
In a double-blind randomized controlled trial, patients with partial-thickness rotator cuff tears or tendinopathy who received PRP had significantly better pain relief and function at three months than those who received a corticosteroid injection, though the difference was not sustained at twelve months (Kwong et al., Arthroscopy, 2021). PRP is a reasonable option for a partial tear when the goal is to avoid or delay surgery. Dr. Mirzayan has lectured nationally on PRP and bone marrow concentrate in rotator cuff surgery, including at the San Diego Shoulder Institute course in 2022, the AAOS Annual Meeting, and AOSSM.
Patellar tendinopathy (jumper's knee)
The evidence here is genuinely mixed. One randomized trial found leukocyte-rich PRP superior to dry needling alone at longer follow-up (Dragoo et al., American Journal of Sports Medicine, 2014), while a later multicenter randomized trial found neither leukocyte-rich nor leukocyte-poor PRP superior to saline (Scott et al., American Journal of Sports Medicine, 2019). Eccentric loading rehabilitation remains the foundation of treatment. Dr. Mirzayan will be candid about what PRP can realistically add.
Biceps tendinopathy and shoulder impingement
Dr. Mirzayan will discuss PRP for these conditions in select cases, but the published evidence is limited and less compelling than for the conditions above. He will say so rather than present PRP as an established treatment where it is not. Anecdotally, he has had great results with PRP injections for treatment of long head biceps tendonitis.
PRP is not appropriate for every patient or every condition. Dr. Mirzayan will evaluate your imaging, your symptoms, and your treatment history before recommending PRP, and will be straightforward with you if he does not believe it is your best option. If you are not sure whether PRP is right for your condition, call (310) 746-5918 and our team will help guide you.
One Fee for Two Injection Sites.
Most physicians charge a separate fee for each site injected during a PRP session. At Dr. Mirzayan's practice, a single procedure fee covers treatment of up to two sites in the same visit, with a small additional for each additional site up to 4 sites. If you have knee arthritis and tennis elbow, or multiple tendon problems that can be addressed at the same time, you will not be charged a full fee per injection. To learn more about PRP pricing or to schedule a consultation, call (310) 746-5918.
The Procedure
PRP is performed in the office without general anesthesia. After your blood is drawn and processed — approximately 20 minutes with the Angel system — the PRP is injected into the treatment site. Ultrasound guidance is often used when clinically appropriate to ensure precise delivery to the target tissue.
Most patients have some soreness at the injection site for a few days following the procedure, which is a normal part of the biologic response. You will be advised to avoid anti-inflammatory medications after the injection, as these can blunt the platelet response. Activity guidelines will be discussed with you based on the site treated and your specific condition.
PRP is not covered by insurance, including Medicare. It is a cash-pay procedure. Call (310) 746-5918 and our team will help guide you on pricing and scheduling.
Frequently Asked Questions
Why didn't PRP work for me when I had it done elsewhere?
The most common reasons are inadequate platelet dose, a system that cannot produce a consistent product, or a mismatch between the PRP formulation and the condition being treated. A leukocyte-rich product injected into an arthritic joint, for example, may not be the right choice. If your previous PRP was prepared with a basic system drawing 8cc – 30 cc of blood, you may not have received enough platelets. Dr. Mirzayan will select the formulation and dose appropriate to your specific condition.
How many treatments will I need?
This depends on the condition. Some patients respond to a single injection. Others benefit from a series of two or three treatments spaced several weeks apart. Dr. Mirzayan will discuss realistic expectations at your consultation.
How long until I feel results?
PRP stimulates a biologic healing process, which takes time. Most patients begin to notice improvement between four and eight weeks following the injection. Full benefit may take three to six months. In the largest tennis elbow trial, the difference between PRP and the control group was not apparent at 12 weeks but was clear at 24 weeks.
Is PRP covered by insurance?
No. PRP is not covered by any insurance plan, including Medicare and Medicaid. It is a self-pay procedure. Call (310) 746-5918 for pricing information.
Do I need imaging before my PRP appointment?
In most cases, yes. Recent X-rays or MRI help confirm the diagnosis and ensure PRP is appropriate for your specific condition. If you do not have recent imaging, Dr. Mirzayan's team can help arrange it.
Is PRP FDA-approved?
No. The FDA has not approved platelet-rich plasma for the treatment of orthopedic conditions. PRP is prepared from your own blood using devices cleared for processing blood components, and its use for musculoskeletal conditions is considered investigational. This does not mean it is unstudied — there are randomized controlled trials supporting its use for several conditions, cited above — but it does mean you should be wary of any clinic presenting PRP as an approved or guaranteed treatment.
Dr. Raffy Mirzayan is a double board-certified orthopedic sports medicine surgeon at DOCS Health, 8436 W 3rd St #800, Los Angeles, CA 90048. To schedule a PRP consultation, call (310) 746-5918 or visit raffymirzayan.com.
This page is for educational purposes and does not constitute medical advice or establish a physician-patient relationship. Dr. Mirzayan is a paid consultant and educator for Arthrex. PRP is not FDA-approved for orthopedic indications and is not covered by insurance.
