Platelet-rich Plasma or PRP injections for joints and tendons are becoming more popular. They form part of the new field of regenerative medicine for use in joints and tendons to reduce pain and encourage healing. But is there evidence that PRP therapy works for conditions such as arthritis and tendonitis?
What is Platelet-rich Plasma?
In summary, platelet-rich plasma, or plasma therapy, is a blood sample with a concentration of platelets greater than whole blood.
Platelet-rich plasma, or PRP, comes from whole blood. We obtain blood from a vein in the patient’s arm. The blood spinning forms different layers: red, white, and plasma. The plasma component contains high platelets and is separated and injected into joints or tendons. First, red and white cells are removed. Next, we remove the red cells as we know that these red cells break down cartilage and stimulate inflammation – an effect we don’t want.
Why do we want a higher concentration of platelets?
In general, different PRP or plasma systems produce different concentrations of platelets. For example, some PRP systems have platelet concentrations above 1.5X whole blood. However, other methods can have greater than 5X absolute blood platelet concentrations. We don’t know whether a higher concentration of platelets has a more significant effect.
Is a higher concentration or platelet count better?
Some practitioners state that a higher concentration or platelet count is more effective than a lower one. However, the evidence for greater effectiveness is questionable. One study suggested 10 billion platelets were required for a better effect. However, this particular study is flawed. On the contrary, multiple cohort studies reveal that people with moderate platelet counts do better than those with higher ones. Until further studies, we recommend a total count of 4-5 million platelets for osteoarthritis in 2-3 injection doses.
What is the difference between leucocyte-poor vs. leucocyte-rich PRP?
Some PRP systems are a little more complicated and increase the concentration of platelets and white cells (leukocytes). Generally, these systems need more blood (50mls) and repeated spins. Some of these systems include N-stride PRP.
Recent evidence suggests that leucocyte-poor is better for arthritis but leucocyte-rich for tendonitis. For example, a recent study found that leukocyte-poor PRP has fewer side effects but is as effective as leucocyte-rich PRP. Conversely, leucocyte-rich PRP is more effective in hip tendonitis or greater trochanteric syndrome.
How do PRP injections reduce pain?
We don’t know the answer yet. However, many studies analyze the effects of PRP on cells and tissue in a lab. Platelets are essential cells that control clotting. They contain a high concentration of growth factors. These growth factors influence inflammation and healing. Injecting plasma therapy into a joint or tendon releases growth factors that improve the local environment. Ultimately, this leads to a lower level of pain and tissue healing.
According to NICE – a body in the UK that assesses treatments – PRP reduces pain and potentially delays the need for a knee replacement.
Do Platelet-rich Plasma injections regenerate cartilage or tendon tissue?
We don’t think so. There is no evidence that any plasma therapy injection can regenerate tissue. However, ongoing studies are looking at this question. Ultimately, the pain-killing effects of PRP are due to a better environment of the joint or tendon rather than tissue regeneration.
Is there evidence for Platelet-rich Plasma injections?
Yes, but evidence exists for only a few common arthritis and tendonitis problems:
- Twenty-three randomised controlled trials show PRP is better than other injections (such as cortisone or hyaluronic acid) for improving pain in KNEE OSTEOARTHRITIS. Also, PRP has shown better results than hyaluronic acid for knee osteoarthritis.
- PRP is better than cortisone for TENNIS ELBOW in some studies. However, a recent Cochrane review showed that PRP was not better than other treatments.
- In PLANTAR FASCIITIS, PRP is better than cortisone in 9 studies. PRP is better than cortisone and safer than surgery in patients with severe plantar fasciitis.
- PRP is better than cortisone for HIP TENDONITIS. A recent review found that PRP is better than cortisone in hip tendonitis after six months and lasts up to 2 years.
- PRP is better than cortisone injections for ROTATOR CUFF TENDONITIS in the medium term. One review found better results for PRP at six months compared to cortisone.
However, platelet-rich plasma has not shown effectiveness for other joints and tendons.
You can read about the other effective treatments for arthritis and other injections for arthritis.
Dr. Masci published a paper summarising the PRP evidence in tendonitis, which is a good resource.
How many PRP injections do you need?
We still need to determine the optimal number of PRP injections. However, for knee osteoarthritis, we recommend 2-3 injections every two weeks. For tendons, we recommend one to two injections two weeks apart.
However, there are second generation PRP systems that provide a higher dose and concentration per injection. One example is Arthrex ACP Max, a novel dual-syringe system that provides 7-10 billion platelets per shot, meaning only one injection is needed rather than 2-3 injections for standard PRP systems.
What to do before PRP therapy
Generally, we suggest PRP therapy works better if you follow the following guidelines:
- Ensure you come in well-hydrated (drink at least a litre of water on the day of the injection).
- Avoid medications that affect platelet function, such as aspirin or ibuprofen, at least two weeks before and for two weeks after a PRP injection.
- Tell your doctor if you have any conditions that may affect the outcome of PRP, such as low platelet count, clotting disorders, or blood tumours.
Will Platelet-rich plasma injections hurt?
Generally, no. Sometimes, the doctor will inject a local anesthetic into the skin to stop the PRP injection from hurting. Also, PRP injections should be done with ultrasound, meaning the injections hurt less. Usually, a few people require pain killers after a PRP injection. Overall, we recommend taking paracetamol or codeine after the injection if needed. Also, we suggest applying ice packs every 4-6 hours, particularly after tendon injections.
What are the potential side effects of platelet-rich plasma injections?
Generally, PRP therapy is safe. However, patients can be sore in the joint or tendon for up to a week. Typically, leucocyte-rich PRP causes a more significant reaction after an injection. Also, the positive effects do not start for at least 2-3 weeks after injection.
Overall, the risk of infection is lower than in other injections and is around one chance in 1500000 injections.
How long should you rest after platelet-rich plasma injections?
Typically, it depends on whether a joint or tendon is injected.
For arthritis, we suggest resting from running or sports for a week. After a few days, you can start a non-impact activity such as swimming or cycling.
For tendons, we recommend a slightly more extended period of time of up to 2 weeks. For example, if you have an injection into a sizeable weight-bearing tendon such as the Achilles, we suggest avoiding explosive activities (such as running) for two weeks.
How long do PRP injections last?
The effect of PRP therapy can vary among patients. For arthritis, two or three injections can last 12-18 months. However, the impact on tendons is much more unpredictable.
What about combined injections: PRP and hyaluronic acid?
Hyaluronic acid is a natural substance in cartilage, joints, and bone. Hyaluronic acid injections, like PRP, are used for knee arthritis and have shown promise. However, recent studies using PRP and hyaluronic acid combined have shown tremendous promise.
A recent study found that combining PRP with hyaluronic acid leads to a more significant effect at 3 and 12 months and fewer side effects than PRP alone.
Dr Masci discusses PRP use in arthritis and tendonitis in a recent webinar.
PRP
Final word from Sportdoctorlondon about platelet-rich plasma injections for arthritis and tendonitis
PRP injections treat knee osteoarthritis, tennis elbow, plantar fasciitis, hip tendonitis, and shoulder tendonitis. However, there is no evidence for other joints or tendons. Generally, PRP therapy is better with an exercise program by an expert such as a physiotherapist.
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I have RA, and happy to Hier there are safer injections . Thank you