In this article, Ross Hauser MD discusses the use of Platelet Rich Plasma Therapy for the treatment of knee osteoarthritis, also known as PRP Knee Injections.

In November 2015, research appeared in the medical journal Arthroscopy, the Journal of Arthroscopic and Related Surgery. 

The 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?

The conclusion? PRP injections offers better symptomatic relief to patients with early knee degenerative changes, and its use should be considered in patients with knee osteoarthritis.1

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 (OA). OA 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.”2 

Often, Prolotherapy is compared to placebo because even dry needling or the injection of nothing will begin a healing response. This follows up other research in Arthroscopy.

New research: PRP effective in stage 3 knee osteoarthritis
Patients with stage 3 osteoarthritis

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.3

In September 2015, 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 (HA) injections or viscosupplementation and placebo injections.4

This research came right on the heels of another paper from earlier in September 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.5

Both studies find themselves in agreement with a paper published online on August 2, 2015 in which investigators compared the effectiveness of multiple and single platelet-rich plasma (PRP) injections as well as hyaluronic acid (HA) 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.6

This research supports other research we reported on in mid July 2015 which added to the growing medical evidence for the effectiveness of Platelet Rich Plasma Therapy for knee osteoarthritis.

In this study a comparison is made 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.7

The pitfalls of basing opinion on a single injection of Platelet Rich Plasma Therapy are many and outlined below. 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 as discussed below.

Some research is now moving away from trying to prove or not prove Platelet Rich Plasma Therapy is effective for knee osteoarthritis. Now research is more trying to explain how PRP works and move forward with treatment guidelines from there.

Another new study acknowledges that Platelet-rich plasma (PRP) contains high concentrations of autologous (from you) growth factors that can repair the knee. Further they found that PRP may also provide 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.

Further, bovine cartilage explants (injection) were found to be influenced by PRP’s ability to stimulate natural knee lubricants. They concluded that PRP significantly stimulates cell proliferation and SZP secretion by articular cartilage and synovium of the human knee joint.8

In other words PRP is acting like hyaluronic acid, except it is healing and regenerating the knee whichhyaluronic acid is not designed to do.

When treating the knee, our medical team utilizes a Comprehensive Prolotherapy injection technique which may include a combination of healing factors. PRP is commonly used in conjunction with Dextrose Prolotherapy and Stem Cell Therapy. If stem cells are used, they would be drawn from the patient and then re-injected into the knee to stimulate tissue regrowth, such as in instances of knee osteoarthritis. This is to ensure that a more thorough treatment is given to the weakened area, versus a one-shot PRP approach. Please see this article for a discussion on the general treatment of osteoarthritis including a detailed description of the PRP therapy injections and for a comparison of types of knee osetoarthritis injection therapy.

In a summary research study researchers were able to conclude that PRP injections were more effective than transcutaneous electrical nerve stimulation (TENS).9


1. 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. Epub 2015 May 29.

2. 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.

3. 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. PubMed PMID: 26834369; PubMed Central PMCID: PMC4713808.

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. [Epub ahead of print]

5. 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. [Epub ahead of print]

6. 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. [Epub ahead of print]

7. 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. [Epub ahead of print]

8. Angoorani H, Mazaherinezhad A, Marjomaki O, Younespour S. Treatment of knee osteoarthritis with platelet-rich plasma in comparison with transcutaneous electrical nerve stimulation plus exercise: a randomized clinical trial. Med J Islam Repub Iran. 2015 Jun 27;29:223. eCollection 2015.

9. 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. [Epub ahead of print]

10. 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. [Epub ahead of print]

11. 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. [Epub ahead of print]

12. 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. [Epub ahead of print]

13. 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. [Epub ahead of print]

14. Del Gaizo DJ, Della Valle CJ. Instability in primary total knee arthroplasty. Orthopedics. 2011 Sep 9;34(9):e519-21. doi: 10.3928/01477447-20110714-46.

15. Graichen H, et al. Ligament instability in total knee arthroplasty–causal analysis. Orthopade. 2007 Jul;36(7):650, 652-6.



Hauser, R. (2015). Platelet Rich Plasma Therapy for Knee Osteoarthritis. Retrieved from