Marc Darrow MD,JD

Over the years we have seen a lot of people with knee problems. Many of them with problems of the patellar tendon. They have had many treatments including, cortisone, physical therapy, rest, some of the them wear big braces on their knees. They are doing a consult with me because they are still looking for help. Can Platelet Rich Plasma Therapy help them? After an email or a phone call we assesses the person’s situation. If we feel they are a realistic candidate for treatment, they come in for a consultation where we can do an examination and come up with a healing program.

  • PRP treatments involve collecting a small amount of your blood and spinning it in a centrifuge to separate the platelets from the red cells. The collected platelets are then injected back into the injured area to stimulate healing and regeneration. PRP utilizes the blood’s platelets and their healing and tissue repair factors.

Published research on Patellar tendinopathy treatments

Patellar tendinopathy is commonly referred to by the more lay terms as “Jumper’s Knee” or “Tennis Knee” because this type of chronic injury is seen obviously in jumping athletes and tennis players. The term basketball knee may also apply as this injury is caused by wear and tear of playing basketball on hard surfaces. So too tennis players. Most tennis players play on the painted cement court.

Various treatment options

When knee pain begins, most people self-treat via instructions from the internet. They will ICE and  COMPRESS the knee with tape or braces. Some will ELEVATE their knee when laying down or sitting in a chair. Much fewer will REST. By now you will probably recognize the familiar RICE anagram or Rest, Ice, Compression, and Elevation as the first line of knee pain treatments along with anti-inflammatory medications found “over-the-counter.”

As the person’s knee worsens they will make their first doctors appointment. Here their doctor may advise them to Rest, Ice, Compress and elevate again. This time the doctor may offer the person a stronger medication. Still failing to resolve their knee pain, the doctor then may move onto stronger medication, a cortisione injection, or physical therapy. Some people will get all these treatments.

For clinicians to maximize the efficacy of conservative treatment options for their patients, they must understand the most up-to-date literature evaluating the potential benefit of taping, bracing, and injections as adjunctive treatments for maximizing treatment success

.A June 2020 study (1) from Stanford University focused on additional treatment options for the two most common causes of front of the knee pain, patellofemoral pain syndrome, and patellar tendinopathy. The researchers wrote: “Conservative management is the first-line treatment for these conditions. For clinicians to maximize the efficacy of conservative treatment options for their patients, they must understand the most up-to-date literature evaluating the potential benefit of taping, bracing, and injections as adjunctive treatments for maximizing treatment success.”

Here they discuss tape, brace, and Prolotherapy, PRP and Stem Cell injections

  • Recent studies of bracing and taping have found them to be helpful for patients in the short-term management of pain and improving function.
  • Injections remain a commonly used treatment for musculoskeletal conditions; however, the evidence for their use in patellofemoral pain and patellar tendinopathy is limited. The use of platelet-rich plasma (PRP), sclerosing (sometimes referred to as Prolotherapy), or stem cell injections is an exciting new area in the treatment of patellar tendinopathy.

I point out this study because many of the people that come into our office have heard something similar in their orthopedisit’s office. Wear a brace if it helps, there is no evidence that PRP or stem cells can help you. So the first thing many of the people who eventually come to visit is ask is, “Is there any research on PRP or stem cells for patellofemoral pain syndrome, and patellar tendinopathy?”

I also want to point out that these same people who come visit us are people who have been on anti-inflammatories, wrap up their legs in ace bandages, ice, may have had a cortisone injections and nothing is really helping. They are here because for some of them are willing to take a chance on PRP or stem cells.

But is there any research?

A December 2018 study examined the role of mesenchymal stem cells in the treatment of tendinopathies.(2) The investigators of this study wrote: “Although (research) attention was mainly focused on their (the stem cell’s) ability to differentiate (change into needed repair cells) and to directly participate to the regeneration process in the past, mesenchymal stem cells have more recently been demonstrated to have further and probably more important therapeutic functions in response to injury like immune modulation and trophic (promoting cellular growth) activities. That is why that they have been defined as “drugstores”. Indeed, they can home in on sites of inflammation or tissue injury and they start to secrete immunomodulatory and trophic agents such as cytokines and growth factors aimed to re-establish physiological homeostasis in response to that environment. (In simpler terms act as an anti-inflammatory and pro-healing agent). So, either as direct player in the process or/and bioactive molecules “drugstores”, mesenchymal stem cells may enhance tissue repair and regeneration and thereby restore normal joint homeostasis.” This research does suggest further studies to validate these positive findings.

A well referenced and cited study from 2012 (3) followed eight mid-20s aged athletes with chronic patellar tendon degeneration. These patients received bone marrow stem cell therapy. The stem cells were taken from the patient’s iliac bone crest and injected into the problem knee. These patients were then followed for 5 years to measure the long-term results of the treatment. Here were the published results:

  • “At 5-year followup, statistically significant improvement was seen for most clinical scores.
  • Seven of eight patients said they would have the procedure again if they had the same problem in the opposite knee and were completely satisfied with the procedure.
  • Seven of 8 patients thought that the results of the procedure were excellent. According to our results, (bone marrow stem cells should be) considered as a potential therapy for those patients with chronic patellar tendinopathy refractory to nonoperative treatments.”

PRP research on patellar tendinopathy

There is limited research as well in the role of PRP in helping patients with patellar tendinopathy. However a 2017 study (4) stated: “These limited studies are encouraging and indicate that PRP injections have the potential to promote the achievement of a satisfactory clinical outcome, even in difficult cases with chronic refractory tendinopathy after previous classical treatments have failed.” One of the studies reviewed was a study from researchers in the Netherlands. In this study, outcomes of patients with patellar tendinopathy treated with platelet-rich plasma injections (PRP) were evaluated to determine whether certain characteristics, such as activity level or previous treatment affected the results. What they found was: “After PRP treatment, patients with patellar tendinopathy showed a statistically significant improvement. In addition, these improvements can also be considered clinically meaningful.”

A 2014 study in The American journal of sports medicine (5) offered these results and assessments:

  • “Chronic patellar tendinopathy is one of the most common overuse knee disorders. Platelet-rich plasma (PRP) appears to be a reliable nonoperative therapy for chronic patellar tendinopathy.”

In this study a total of 28 athletes (17 professional, 11 semiprofessional) with chronic patellar tendinopath refractory to nonoperative management were prospectively included for ultra-sound guided pure PRP injections into the site of the tendinopathy. The same treating physician at a single institution performed 3 consecutive injections 1 week apart, with the same PRP preparation used. Tendon healing was assessed with MRI at 1 and 3 months after the procedure.


  • Patients showed significantly improved at the 2-year follow-up.
  • Twenty-one of the 28 athletes returned to their presymptom sporting level at 3 months (range, 2-6 months) after the procedure.
  • Follow-up MRI assessment showed improved structural integrity of the tendon at 3 months after the procedure and complete return to normal structural integrity of the tendon in 16 patients (57%).
  • Seven patients did not recover their presymptom sporting level (among them, 6 were considered treatment failures): 3 patients returned to sport at a lesser level, 1 patient changed his sport activity (for other reasons), and 3 needed surgical intervention.


In this study, application of 3 consecutive ultrasound-guided PRP injections significantly improved symptoms and function in athletes with chronic patellar tendinopathy and allowed fast recovery to their pre-symptom sporting level. The PRP treatment permitted a return to a normal architecture of the tendon as assessed by MRI.

A July 2018 study (6) wraps it up succinctly. The study author wrote: “Patellar tendons seem to benefit from PRP injections.”

As stated at the top of this article. We have been offering regenerative medicine injections for more than 23 years. Empirical and in office data shows a benefit for many. Will these treatments work for everyone? No. Email me with the form below so we can assess whether or not these treatments would be viable for you.

Do you have questions? Ask Dr. Darrow


A leading provider of stem cell therapy, platelet rich plasma and prolotherapy

PHONE: (800) 300-9300 or 310-231-7000

1 Sisk D, Fredericson M. Taping, Bracing, and Injection Treatment for Patellofemoral Pain and Patellar Tendinopathy [published online ahead of print, 2020 Jun 4]. Curr Rev Musculoskelet Med. 2020;10.1007/s12178-020-09646-8. doi:10.1007/s12178-020-09646-8
2 Abat F, Alfredson H, Cucchiarini M, Madry H, Marmotti A, Mouton C, Oliveira JM, Pereira H, Peretti GM, Spang C, Stephen J, van Bergen CJA, de Girolamo L. Current trends in tendinopathy: consensus of the ESSKA basic science committee. Part II: treatment options. J Exp Orthop. 2018 Sep 24;5(1):38. doi: 10.1186/s40634-018-0145-5. PMID: 30251203; PMCID: PMC6153202.
3 Pascual-Garrido C,et al. Treatment of chronic patellar tendinopathy with autologous bone marrow stem cells: a 5-year-followup. Stem Cells Int. 2012;2012:953510. doi: 10.1155/2012/953510. Epub 2011 Dec 18.
4. Gosens T, Den Oudsten BL, Fievez E, van ‘t Spijker P, Fievez A. Pain and activity levels before and after platelet-rich plasma injection treatment of patellar tendinopathy: a prospective cohort study and the influence of previous treatments.Int Orthop. 2012 Apr 27. [Epub ahead of print]
5. Charousset C, Zaoui A, Bellaiche L, Bouyer B. Are multiple platelet-rich plasma injections useful for treatment of chronic patellar tendinopathy in athletes? a prospective study. The American journal of sports medicine. 2014 Apr;42(4):906-11.
6 Filardo G, Di Matteo B, Kon E, Merli G, Marcacci M. Platelet-rich plasma in tendon-related disorders: results and indications. Knee Surgery, Sports Traumatology, Arthroscopy. 2018 Jul;26(7):1984-99. — 1613

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