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 stem cell therapy and 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.
  • Stem cell therapy involves the use of your own bone marrow derived stem cells or donated umbilical cord blood derived stem cells. These are explained further in the research below.

Published research on Patellar tendinopathy treatments

A December 2018 study examined the role of mesenchymal stem cells in the treatment of tendinopathies.(1) The investigators of this study wrote: “Although attention was mainly focused on their ability to differentiate and to directly participate to the regeneration process in the past, mesenchymal stem cells (MSCs) 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 and 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 (2) 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.”

A 2017 study (3) featured the role of umbilical cord blood-mesenchymal stem cells in tendon repair. Here the researchers suggested:

“Emerging cell sources for tendon repair include peripheral blood MSC, umbilical cord blood-mesenchymal stem cells (UCB-MSCs), and periodontal ligament cells. Studies have shown:

  • Allogeneic UCB-MSCs injected into naturally occurring tendinitis of the superficial digital flexor tendon led to higher performance and strength, as well as improved healing as assessed by ultrasound imaging
  • Efficacy of UCB-MSCs in improving tendon-bone healing following anterior cruciate ligament reconstruction has also been demonstrated in a rabbit model.
  • Injection of UCB-MSCs into the interface between the bone tunnel and tendon graft improved the histologic appearance in the bone-tendon interface.

More research is called for, including that which examines the benefit of stem cells for the patella tendon.


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.”

As stated at the top of this article. We have been offering regenerative medicine injections for more than 20 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

Stem cell and PRP injections for musculoskeletal conditions are not FDA approved. We do not treat disease. We do not offer IV treatments. There are no guarantees that this treatment will help you. Prior to our treatment, seek advice from your medical physician. There is controversy in the medical community about whether umbilical cord blood stem cells are alive or dead, and which type of stem cell may be appropriate.

Neither Dr. Darrow, nor any associate, offer medical advice from this transmission. This information is offered for educational purposes only. The transmission of this information does not create a physician-patient relationship between you and Dr. Darrow or any associate. We do not guarantee the accuracy, completeness, usefulness or adequacy of any resource, information, product, or process available from this transmission. We cannot be responsible for the receipt of your email since spam filters and servers often block their receipt. If you have a medical issue, please call our office. If you have a medical emergency, please call 911.

1 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.
2 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.
3 Liu L, Hindieh J, Leong DJ, Sun HB. Advances of stem cell based-therapeutic approaches for tendon repair. J Orthop Translat. 2017 Apr 13;9:69-75. doi: 10.1016/ PMID: 29662801; PMCID: PMC5822968.
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]