In this article, we are updating research and clinical observations in the use of Platelet Rich Plasma Therapy (PRP) for the treatment of knee osteoarthritis.
Research is now moving away from trying to prove or not prove out Platelet Rich Plasma Therapy as being an effective treatment for knee osteoarthritis. PRP does work – this has been made clear by the mounting evidence from independent medical researchers.
Part of that evidence is a study published in the American medical journal Arthroscopy. Here doctors from Chongqing Medical University in China suggested that PRP injections were 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. These injections included saline placebo, Hyaluronic Acid, ozone and corticosteroids. Further, they found that PRP did not increase the risk of adverse events compared with Hyaluronic Acid and saline.(1)
This research is among a large number of studies offering convincing evidence that PRP helps patients with knee injuries and knee instability. Please see our article on What is Platelet rich Plasma Therapy for a discussion on how PRP works.
At Caring Medical and Rehabilitation Services, we provide PRP Prolotherapy. This is PRP Therapy augmented by dextrose Prolotherapy. This is explained in the video below by Dr. Hauser. Please read on below PRP success is more than a one-time injection.
PRP Knee Injections heal injured knees by changing the diseased knee joint environment to a repairing knee environment by waking up native stem cells in the knee
The basics behind how PRP works for knee osteoarthritis is summarized in research from doctors at the University of California. In their study in the publication Tissue engineering. Part B, Reviews, the doctors suggest that 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.(2)
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.
Is PRP a knee lubricant like gel shots?
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.(3)
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 a better knee lubricant than hyaluronic acid?
The second Chinese study, published in the Orthopaedic surgery and research out of London also suggested that current evidence indicates that, compared with Hyaluronic Acid 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.(4)
Doctors in Thailand published in slightly earlier research that PRP injection 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. (5)
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) The researchers also speculated that PRP may have worked better had the patient received multiple PRP injections. PRP is not a one-shot therapy
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)
Here is a study on PRP effective in patients with stage 3 osteoarthritis. Doctors tested the number of injections and frequency.
Doctors in Turkey publishing in the Journal of physical therapy science, 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)
- 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 injections or viscosupplementation and placebo injections.(9)
- 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.(10)
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.(11)
Is PRP better anti-inflammatory than Cortisone?
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.(12)
In a paper published by researchers at the University of Barcelona in the Journal of Orthopedic Sports Medicine, the use of PRP injections for advanced osteoarthritis was tested.
They found a single PRP intra-articular injection is effective for relieving pain and improving activities of daily living and quality of life in late-stage knee osteoarthritis. For patients with late-stage knee osteoarthritis who are 67 years or older, 1 intra-articular injection of PRP has similar results to 1 shot of corticosteroid.(13)
A 2017 study in the American Journal of Sports Medicine lead by Brandon Cole MD of Rush University Medical Center found PRP was involved in decreasing 2 proinflammatory cytokines, which suggest that the anti-inflammatory properties of PRP may contribute to an improvement of symptoms.(14)
The difference of course is that you can offer more than one PRP injection or combine it with comprehensive Prolotherapy for knee osteoarthritis to gain better results. Typically a doctor will not recommend multiple corticosteroid injection because of the negative effects.
How does PRP compare to Ozone Therapy?
In research from February 2017, Turkish researchers publishing in the medical journal Knee surgery, sports traumatology, arthroscopy compared treatment effectiveness in patients with knee osteoarthritis given an intra-articular injection of platelet-rich plasma, hyaluronic acid or ozone gas.
A total of 102 patients with mild-moderate and moderate knee osteoarthritis were chosen who had at least a 1-year history of knee moderate pain (a four out of 10 pain rating or worse)
- Group 1 (platelet-rich plasma group) received intra-articular injection of PRP × 2 doses,
- Group 2 (hyaluronic acid group) received a single dose of hyaluronic acid,
- and Group 3 (Ozone group) received ozone × four doses.
- At the end of the 1st month after injection, significant improvements were seen in all groups.
- In the 3rd month, the improvements were similar in platelet-rich plasma group and hyaluronic acid group , while those in Ozone group were lower.
- At the 6th month, while the clinical efficacies of platelet-rich plasma and hyaluronic acid were similar and continued, the clinical effect of ozone had disappeared
- At the end of the 12th month, platelet-rich plasma was determined to be both statistically and clinically superior to hyaluronic acid.(15)
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.(16)
This is alluded to in another paper 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. “(17)
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 osteoarthritis injection treatments including Prolotherapy.
Number of PRP injections needed how long is recovery?
Frequently patients will ask: What is the healing or recovery time with PRP?
The research mentioned above on the number of treatments is providing the evidence called for in earlier works. Testing whether or not Platelet-rich plasma (PRP) provides symptomatic relief in early knee osteoarthritis in athletes, researchers looked at 78 patients with bilateral knee osteoarthritis. The patients were then divided randomly into three groups.
- Group A (52 knees) received a single injection of PRP
- Group B (50 knees) received 2 injections of PRP 3 weeks apart
- Group C (46 knees) received a single injection of normal saline
The three groups were compared with each other and no improvement was noted in group C as compared with groups A and B.
The next part is interesting: there was no difference between groups A and B, which means that a single dose of PRP is as effective as two injections to alleviate symptoms in early knee osteoarthritis. The results, however, deteriorate after six months. Both groups treated with PRP had better results than did the group injected with saline only.
Other than the fact that the PRP was found effective at alleviating symptoms of osteoarthritis in the knee is the subsequent findings. Two PRP injections were no more effective than one and that the results deteriorated after six months.(18)
Now these findings are somewhat in agreement with other recent research that suggests a single dose of PRP worked very well for a six-month time period but the results deteriorated.(19)
Side effects of PRP include general side effects concerning injections Pain and soreness at the site of the injections, Infection, Blood clot, Bruising
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