PRP therapy: what platelet-rich plasma can and cannot do
Published: Author: Mikheil Mikeladze, MD
PRP, or platelet-rich plasma, is a preparation made from the patient’s own blood and injected into a joint or a damaged tendon. In knee osteoarthritis it gives roughly the same short-term results as hyaluronic acid, and in tendon pain it sometimes helps. PRP does not restore cartilage.
What PRP is and how it is prepared
PRP (platelet-rich plasma) is plasma with an increased concentration of platelets. Platelets are blood cells that stop bleeding, and they also contain substances involved in tissue healing. The idea is simple: deliver these substances in concentrated form directly to where the problem is.
The procedure has three steps:
- Blood is taken from a vein, just like for a routine blood test.
- The blood is processed in a special centrifuge, which separates the platelet-rich part.
- The resulting plasma is injected into the joint or around the tendon under ultrasound guidance.
Because the preparation is made from your own blood, there is no risk of an allergic reaction to a foreign substance.
Where PRP is used and what we know about it
There is a lot of research on PRP, but the results differ from condition to condition. So I will be honest about what we know.
| Condition | What we know |
|---|---|
| Knee osteoarthritis | Roughly the same short-term results as hyaluronic acid; does not restore cartilage |
| Tennis elbow | Helps in some studies when exercise has not been enough |
| Plantar fasciitis | Considered when stretching, footwear and other methods are not enough |
| Long-standing tendon pain elsewhere | Mixed results; the decision is individual |
| Hip osteoarthritis | Covered in a separate article: injection therapy |
On other causes of knee pain and their treatment: knee pain. On tendon pain in general: tendinopathy.
How a PRP injection is done
The whole procedure takes place in one visit. The time between taking blood and the injection is needed for processing in the centrifuge, and the injection itself takes a few minutes.
I give the injection under ultrasound guidance. The screen shows the needle and the tissue, so the plasma goes exactly where it is needed. This is especially important for tendons: the damaged area is often small and can only be seen on the screen.
You go home the same day, with advice to spare the treated area for a while. In the first days, local pain or a feeling that the area is “tight” is common and settles on its own.
Some medicines weaken platelet function, so we review your medicines before the procedure. Your doctor will tell you which one to pause and for how long: do not stop any medicine on your own.
What to expect
PRP does not work as fast as a steroid. A steroid injection reduces pain within days, while the effect of PRP shows gradually, over weeks. That is why we assess the result after several weeks, not the next day.
PRP is one part of treatment. With tendon pain the key is still gradual, measured exercise: the injection reduces pain and makes exercise easier, but it is exercise that strengthens the tendon. With osteoarthritis, the same applies to weight, muscle strength and spreading the load correctly. More detail: conservative treatment.
PRP, steroid or hyaluronic acid
| PRP | Steroid | Hyaluronic acid | |
|---|---|---|---|
| What it is made from | Your own blood | Corticosteroid and local anaesthetic | Ready-made product |
| How fast it works | Gradually, over weeks | Within days | Gradually, over weeks |
| For tendons | Sometimes considered | With caution; not into load-bearing tendons | Not used |
| For joints | In osteoarthritis | With active inflammation | In osteoarthritis |
On steroid injections in detail: steroid injection. On hyaluronic acid: hyaluronic acid.
Who PRP is not suitable for
- with an active infection, in the joint or on the skin;
- with some disorders of platelets or blood clotting;
- in end-stage osteoarthritis, when the joint space has practically disappeared: the expected result is small;
- while the diagnosis is unclear.
Key points
- PRP is made from your own blood and works through substances in platelets.
- In knee osteoarthritis it gives roughly the same short-term results as hyaluronic acid.
- In tendon pain it sometimes helps, but the evidence is mixed.
- It does not restore cartilage and cannot replace exercise.
- I give the injection under ultrasound guidance, and we assess the result after several weeks.
If a joint or tendon has hurt for more than a week, book a consultation: we will see whether PRP suits you.
Common questions
Does PRP restore cartilage?
No. According to current evidence, PRP does not restore worn cartilage and does not widen the joint space. Its real purpose is to reduce pain and improve function. If someone promises you that PRP will "regenerate" cartilage, that promise deserves caution.
How many injections do I need?
It depends on what we are treating and how the body responds. Sometimes one injection is given, sometimes several, at intervals. We agree on the number in advance and assess the result after each injection.
How soon will I feel a result?
PRP does not work as fast as a steroid. Change usually appears gradually, over weeks, so it is not worth drawing conclusions in the first days. Keeping a diary helps: how pain changed when walking, at night and under load.
Who should not have PRP?
PRP is not given with an active infection or with some disorders of platelets or blood clotting. With cancer, the decision is individual. We discuss blood thinners and anti-inflammatory medicines before the procedure: your doctor will tell you which ones to pause and for how long.
Is PRP better than hyaluronic acid?
In knee osteoarthritis they work roughly the same in the short term. The difference lies elsewhere: PRP is made from your own blood, while hyaluronic acid is a ready-made product. For long-standing tendon pain hyaluronic acid is not used, while PRP is sometimes considered. We make the choice at the consultation, based on the state of the joint.
This text is educational and does not replace a consultation. A diagnosis and a treatment plan can only be set after a personal examination.
Have a question about your own case?
At the consultation we look at your X-ray together and I tell you what stage the joint is at and what the next step is. Seeing a surgeon does not mean surgery.
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Read next
- Injection therapySteroid injection: when it helps and why it is not done oftenA steroid injection quickly reduces inflammation and pain, but it does not cure the cause. When it is worth it, how often it can be repeated and what to know beforehand.
- Injection therapyHyaluronic acid injections in the knee: who they help and for how longA hyaluronic acid injection temporarily improves the properties of joint fluid and reduces pain in osteoarthritis. Who it helps, how long the effect lasts and what it cannot do.
- Other joints and spineShoulder pain: causes and treatment without surgeryShoulder pain is most often caused by tendon overload, frozen shoulder, osteoarthritis or the neck. How to tell them apart and when exercise and physiotherapy are enough.
