Knee Osteoarthritis and Platelet Rich Plasma Therapy Injections

The effectiveness of Platelet rich Plasma injections for knee osteoarthritis  has been made clear by mounting evidence from independent medical researchers.

Here we will briefly touch on two new studies from Chinese researchers and that from Thailand that have now been added to the mounting evidence.

These studies show PRP injections to be more effective in the treatment of knee osteoarthritis, in terms of pain relief and self-reported function improvement at three, six, and twelve months follow-up, compared with other injections, including saline placebo, Hyaluronic Acid, ozone, and corticosteroids.

The first study published in Arthroscopy : the journal of arthroscopic & related surgery, gave evidence that when compared with Hyaluronic Acid injections (examples of which are under these brand names Euflexxa, Gel-One, Hyalgan, Hyalgan LL, Monovisc, Orthovisc, Supartz and Supartz FX) and saline, intra-articular PRP injection may have more benefit in pain relief and functional improvement in patients with symptomatic knee osteoarthritis at 1 year postinjection.1

In the second study published in the Journal of orthopaedic surgery and research, doctors found Intra-articular PRP injections more effective in the treatment of knee osteoarthritis in terms of pain relief and self-reported function improvement at 3, 6 and 12 months follow-up, compared with other injections, including saline placebo, Hyaluronic Acid injection ozone, and corticosteroids.2

This research continued a trend on early findings including research in the journal Knee surgery, sports traumatology, arthroscopy where doctors also found PRP injections improved patient symptoms and function when compared to Hyaluronic Acid and placebo suggesting that PRP injection is more effective than Hyaluronic Acid injection and placebo in reducing symptoms and improving function and quality of life. 3

In the medical journal Arthroscopy, the Journal of Arthroscopic and Related Surgery, research sought to answer Does Intra-articular Platelet-Rich Plasma Injection Provide Clinically Superior Outcomes Compared With Other Therapies in the Treatment of Knee Osteoarthritis?

This study examined previously published studies and concluded that PRP injections are a viable treatment for knee osteoarthritis and has the potential to lead to symptomatic relief for up to 12 months.6

In the accompanying editorial James H. Lubowitz, MD writes, “(the authors) pose a controversial question and ultimately conclude that platelet-rich plasma (PRP) is a valuable treatment for knee osteoarthritis .

Osteoarthritis pain is epidemic, biologics hold promise, pain research is limited to some extent by placebo effect, and the ultimate goal must be chondroprotection, or even cartilage restoration, in addition to symptomatic relief. That said, PRP injection does result in improved knee pain and function in patients with osteoarthritis.”7 

PRP and Stage III Osteoarthritis

Here is a study on PRP effective in patients with stage 3 osteoarthritis published in the Journal of physical therapy science. Doctors tested the number of injections and frequency.

Doctors assessed PRP applications in a group of patients in their mid-50’s. Three groups were selected for PRP injections.

  • Group 1 received a single injection of PRP,
  • Group 2 received two injections of PRP two weeks apart,
  • Group 3 received three injections of PRP at 2-weeks intervals.

Statistically significant improvements were noted in all of the evaluated measures in all of the groups.

Conclusion: PRP is an effective treatment for functional status and pain in moderate knee osteoarthritis and a minimum of two injections is appropriate.8

  • Doctors writing in the medical journal Arthroscopy suggested that platelet-rich plasma (PRP) injection significantly improved patient-reported outcomes in patients with symptomatic knee osteoarthritis at 6 and 12 months postinjection and that PRP was superior to hyaluronic acid injections or viscosupplementation and placebo injections.9
  • This research came right on the heels of another paper in the journal Knee surgery, sports traumatology, arthroscopy which came to the same results. They found that in short-term outcomes of one year or less –  PRP injection has improved functional outcomes when compared to hyaluronic acid and placebo. The researchers concluded that PRP has the potential to be the treatment of choice in patients with mild-to-moderate knee osteoarthritis who have not responded to conventional treatment.10

Both studies find themselves in agreement with a paper first published online in 2015 and then in print edition in 2017 also appearing in the Knee surgery, sports traumatology, arthroscopy in which investigators compared the effectiveness of multiple and single platelet-rich plasma injections as well as hyaluronic acid injections in different stages of osteoarthritis of the knee.

One hundred and sixty-two patients with different stages of knee osteoarthritis were randomly divided into four groups receiving:

  • three dose injections of platelet-rich plasma,
  • one injection of platelet-rich plasma,
  • one injection of hyaluronic acid or
  • a saline injection as a control. Please see our article on Prolotherapy that shows saline injection may not be the best control.

The test patients were separated into two groups: early osteoarthritis  and advanced osteoarthritis.

The patients were evaluated before the injection and at the 6-month follow-ups.

There was a statistically significant improvement in all the treatment groups compared with the control group.

The knee scores of patients treated with three PRP injections were significantly better than those patients of the other groups.

There was no significant difference in the scores of patients injected with one dose of PRP or hyaluronic acid.

However, there was no significant difference in the clinical results of patients with advanced osteoarthritis among the treatment groups. (Note for three shots of PRP). For an experienced Prolotherapist, PRP may be used in conjunction with other types of Prolotherapy to ensure the root of the problem is fully addressed and treated.11

In November 2017, researchers reported on the benefits of PRP in knee osteoarthritis and reduced muscle strength in the affected knee. Published in the American journal of physical medicine & rehabilitation, the study showed PRP treatment significantly improves pain, stiffness, and disability in patients with knee osteoarthritis compared to normal saline (placebo) treatment. Additionally, to enhance PRP recovery muscle strength training was recommended.17

Also in November 2017, in the International journal of rheumatic diseases, researchers reported a summary of the most recent findings on the benefits of PRP for knee osteoarthritis.

This study performed an overview of the research to provide recommendations for PRP use in knee osteoarthritis patients through the best evidence. “They concluded that  PRP is an effective intervention in treating knee osteoarthritis without increased risk of adverse events.”18

Convinced that PRP helps, research now is concerning itself more in trying to explain how to utilize PRP and how it goes about healing knee injuries and knee instability. This knowledge will allow doctors to move forward with treatment recommendations and guidelines.

PRP Knee Injections changes the diseased knee joint environment to healing by waking up stem cells

Publishing in the quarterly review of the Tissue Engineering & Regenerative Medicine International Society, doctors at the University of California says PRP injections cause positive, beneficial, and healing cellular changes in the joint environment. These changes help move the knee from degenerative knee disease to a healing and regenerating knee joint. Healing includes: regeneration of articular cartilage, increasing the volume of natural knee lubricants, and waking up the stem cells present in the knee to assist in the transformation to healing environment.4

In the present study, the researchers wrote: PRP modulates the repair and regeneration of damaged articular cartilage in the joints and delays the degeneration of cartilage by stimulation of mesenchymal stem cell migration, proliferation, and differentiation into articular chondrocytes (the cells of cartilage).

What this last sentence means is that stem cells in the knees, responsible for repair on many levels, migrate because PRP call them to the site of the injury, proliferate – make more of themselves, differentiate – change themselves into cartilage.

In addition PRP reduces the pain by decreasing inflammation of the synovial membrane where pain receptors are localized. Synovial membrane is a protective layer of connective tissue that is also responsible for creating synovial fluid that lubricates the joints.

PRP is a knee lubricant

As amazing as the above research is – it is another in the progression of studies. Previously in 2015, the same University of California Davis researchers speculated that PRP provided the lubrication needed to protect the cartilage. The study researchers summarized that intra-articular injections of PRP have the potential to relieve the symptoms of osteoarthritis in the knee and that there is an influence on superficial zone protein (SZP) which is a boundary lubricant in articular cartilage and plays an important role in reducing friction and wear and therefore is critical in cartilage regeneration.5

In other words PRP is acting like hyaluronic acid, except it is healing and regenerating the knee which hyaluronic acid is not designed to do – please see that article where I also discuss the combined use of hyaluronic acid and PRP for knee osteoarthritis.

Is PRP better at relieving pain than Cortisone?

A study published in The Journal of sports medicine and physical fitness made a comparison between the effects of a one-time injection of PRP and corticosteroid  (cortisone shot) for the patients suffering from osteoarthritis.

Patients suffering from Grade II or Grade III  knee osteoarthritis were randomly divided into two groups: intra articular injection of PRP and cortisone.

Forty-one participants (48 knees) were involved in the research (66.7% women with and average age of 61).

Compared to the group treated with corticosteroid, PRP showed significant results for:

  • pain relief
  • being symptom free,
  • activities of daily living and quality of life

But sporting ability was not different between the 2 groups. PRP prescription was significantly more helpful for relieving patients’ pain compared to corticosteroids .It’s also notable that using PRP was more helpful in improving the 20-meter-walk test than corticosteroid treatment but none of the treatments had any impact on active flexion Range of Motion ،passive flexion Range of Motion and flexion contracture.

This study demonstrated that one shot of PRP injection, decreased joint pain more and longer-term, alleviated the symptoms, and enhanced the activity of daily living and quality of life in short-term duration in comparison with corticosteroid.12

PRP success is more than a one-time injection- Number of PRP treatments for Osteoarthritis of the knee

The pitfalls of basing opinion on a single injection of Platelet Rich Plasma Therapy are many. Fortunately in the above research, the study authors make it clear they were testing one injection of PRP vs one injection of cortisone. In other studies the entire classification of PRP can be given a positive or negative outcome based on a single injection – this of course would not be accurate.

Some physicians may use PRP as a single dose treatment rather than as part of a comprehensive treatment program. Used this way PRP may not be as effective. For this reason, some researchers see the components, healing mechanisms, and outcomes of PRP as challenging, and though the treatment has reparative functions in osteoarthritis of the knee even with the single dose usage, they would like to see a standardized protocol as suggested in research published in the Archives of physical medicine and rehabilitation.13 

This is alluded to in another paper published in the Spanish language medical journal Cirugía y cirujanos (surgery and surgeons) which says:

“The number of publications demonstrating the therapeutic and regenerative benefits of using platelet-rich plasma as a treatment for knee osteoarthritis has been increasing in recent years. In spite of encouraging results, there are still only a few randomised control studies with strong clinical evidence, lacking clarity on points such as the optimum formulation or the mechanism of action of platelet-rich plasma. “14

For more information, please contact a doctor on this website.


1. Dai WL, Zhou AG, Zhang H, Zhang J. Efficacy of Platelet-Rich Plasma in the Treatment of Knee Osteoarthritis: A Meta-analysis of Randomized Controlled Trials. Arthroscopy. 2016 Dec 22. pii: S0749-8063(16)30780-0.

2. Shen L, Yuan T, Chen S, Xie X, Zhang C. The temporal effect of platelet-rich plasma on pain and physical function in the treatment of knee osteoarthritis: systematic review and meta-analysis of randomized controlled trials. J Orthop Surg Res. 2017 Jan 23;12(1):16.

3. Kanchanatawan W, Arirachakaran A, Chaijenkij K, Prasathaporn N, Boonard M, Piyapittayanun P, Kongtharvonskul J. Short-term outcomes of platelet-rich plasma injection for treatment of osteoarthritis of the knee. Knee Surg Sports Traumatol Arthrosc. 2016 May;24(5):1665-77.

4. Sakata R, Reddi AH. Platelet-Rich Plasma Modulates Actions on Articular Cartilage Lubrication and Regeneration. Tissue Eng Part B Rev. 2016 Apr 25.

5. Sakata R, McNary SM, Miyatake K, Lee CA, Van den Bogaerde JM, Marder RA, Reddi AH. Stimulation of the Superficial Zone Protein and Lubrication in the Articular Cartilage by Human Platelet-Rich Plasma. Am J Sports Med. 2015 Mar 26. pii: 0363546515575023.

6. Campbell KA, Saltzman BM, Mascarenhas R, Khair MM, Verma NN, Bach BR Jr, Cole BJ. A Systematic Review of Overlapping Meta-analyses. Arthroscopy. 2015 Nov;31(11):2213-21. doi: 10.1016/j.arthro.2015.03.041.

7. Lubowitz JH. Editorial Commentary: Platelet-Rich Plasma Improves Knee Pain and Function in Patients With Knee Osteoarthritis. Arthroscopy. 2015 Nov;31(11):2222-3. doi: 10.1016/j.arthro.2015.08.022

8. Kavadar G, Demircioglu DT, Celik MY, Emre TY. Effectiveness of platelet-rich plasma in the treatment of moderate knee osteoarthritis: a randomized prospective study. J Phys Ther Sci. 2015 Dec;27(12):3863-7. doi: 10.1589/jpts.27.3863. Epub 2015 Dec 28.

9. Meheux CJ, McCulloch PC, Lintner DM, Varner KE, Harris JD. Efficacy of Intra-articular Platelet-Rich Plasma Injections in Knee Osteoarthritis: A Systematic Review. Arthroscopy. 2015 Sep 29. pii: S0749-8063(15)00659-3. doi: 10.1016/j.arthro.2015.08.005.

10. Kanchanatawan W et al. Short-term outcomes of platelet-rich plasma injection for treatment of osteoarthritis of the knee. Knee Surg Sports Traumatol Arthrosc. 2015 Sep 19.

11. Görmeli G, Görmeli CA, Ataoglu B, Çolak C, Aslantürk O, Ertem K. Multiple PRP injections are more effective than single injections and hyaluronic acid in knees with early osteoarthritis: a randomized, double-blind, placebo-controlled trial. Knee Surg Sports Traumatol Arthrosc. 2015 Aug 2. [Pubmed]

12. Forogh B, Mianehsaz E, Shoaee S, Ahadi T, Raissi GR, Sajadi S. Effect of single injection of Platelet-Rich Plasma in comparison with corticosteroid on knee osteoarthritis: a double-blind randomized clinical trial. J Sports Med Phys Fitness. 2015 Jul 14.

13. Chang KV, Hung CY, Aliwarga F, Wang TG, Han DS, Chen WS. Comparative Effectiveness of Platelet-Rich Plasma Injections for Treating Knee Joint Cartilage Degenerative Pathology: A Systematic Review and Meta-Analysis. Arch Phys Med Rehabil. 2013 Nov 27. pii: S0003-9993(13)01212-4. doi: 10.1016/j.apmr.2013.11.006.

14. Simental-Mendía MA, Vílchez-Cavazos JF, Martínez-Rodríguez H. [Platelet-rich plasma in knee osteoarthritis treatment].Cir Cir. 2015 Jun 23. pii: S0009-7411(15)00100-0. doi: 10.1016/j.circir.2014.06.001. [Pubmed]

15. Patel S, Dhillon MS, Aggarwal S, Marwaha N, Jain A. Treatment With Platelet-Rich Plasma Is More Effective Than Placebo for Knee Osteoarthritis: A Prospective, Double-Blind, Randomized Trial. Am J Sports Med. 2013 Jan 8. [Pubmed]

16. Halpern B, Chaudhury S, Rodeo SA, Hayter C, Bogner E, Potter HG, Nguyen J. Clinical and MRI Outcomes After Platelet-Rich Plasma Treatment for Knee Osteoarthritis. Clin J Sport Med. 2012 Dec 12. [Pubmed]

17. Wu YT, Hsu KC, Li TY, Chang CK, Chen LC. Effects of platelet-rich plasma on pain and muscle strength in patients with knee osteoarthritis. American journal of physical medicine & rehabilitation. 2017 Nov. [Pubmed]

18. Xing D, Wang B, Zhang W, Yang Z, Hou Y, Chen Y, Lin J. Intra‐articular platelet‐rich plasma injections for knee osteoarthritis: An overview of systematic reviews and risk of bias considerations. International journal of rheumatic diseases. 2017 Dec 5. [Pubmed]

5 thoughts on “Knee Osteoarthritis and Platelet Rich Plasma Therapy Injections

  1. Where is the prolo-therapy provider that is closest to North Dakota that utilizes the enriched injections ?

  2. This is a wonderful article. I recently had shoulder surgery and need a left knee replacement. My right knee is arthritic plus need a 6th foot surgery. I need pain management until my knee replacement and I plan on getting my referral changed to your office in hopes I’ll be a candidate for PRP in my right knee. Hope to see you soon.

  3. This article was updated January 18, 2018 to reflect evidence from two November 2017 studies

  4. Since Platelet Rich Plasma Therapy Injections work so well when are insurance companies coming on board. Without insurance I can’t afford the injections.

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