The great PRP scandal

PRP (or platelet rich plasma) has become a very popular intervention for tendon and joint injuries over the last five years.

It is particularly popular in Melbourne. In fact there have been some Sports Medicine clinics open recently advertising this as one of their main intervention options!

What is PRP?

Basically PRP involves your own blood being taken from a vein (normally in your arm) – then placed in a centrifuge and ‘spun down’ to separate the blood into 3 products – red blood cells, platelet poor plasma, and platelet rich plasma.

The last item – the PRP – is kept, and injected into the affected tissue.

PRP contains many ‘growth factors’ which are theorised to have a benefit in tissue healing.

Injuries that the PRP injections are used for include tendinopathies (tendinitis) such as Achilles tendinopathy, patella tendinopathy, tennis elbow and gluteal tendinopathy, knee joint and hip joint osteoarthritis, labral tears of the hip and shoulder, and ITB syndrome.

The cost is significant – anywhere from $200 up. The suggested number of injections varies but is normally two to four injections over a six to eight week period.

Unfortunately there is no, high quality evidence that PRP works! I’ll take a brief look at some of the research that has looked at PRP injections

Firstly, a Cochrane review from 2014 looked at a review of 19 trials of PRP – with a control group of placebo injection, blood injection (non PRP), dry needling or no injection.

Most injuries treated were tendinopathies, e.g. tennis elbow, patella tendinopathy, Achilles tendinopathy).

The summary of the trial showed no differences between groups in the short, medium and long term follow up.

There was a very small difference in pain at short term only – but no differences in medium or long term follow up.

A 2009 paper from the USA published an excellent summary of previous human research for PRP.

Unfortunately most of the research articles covered has poor research design which makes us have caution when interpreting their results.

More recently, a review of 4 studies on PRP for tennis elbow showed strong evidence that PRP is unhelpful for this condition.

There are some terrific anecdotes about PRP – I’ve had several patients report ‘great results’ with the PRP. This may be for a few reasons:

• PRP may work for a specific subgroup, or type, of tendon injury or joint injury. No one has published anything discussing exactly what type of specific problem may benefit.
• Placebo is powerful! Particularly expensive placebo treatments! Remember the cost of the medical consultations plus injections can be well in excess of $1,000.
• Regression to the mean. The reality is that people having these injections may only have been sore for a few months, and may have got better anyway! Particularly with a couple of weeks of enforced rest as is often encouraged after these PRP injections

Remember, there are proven treatments for these conditions.

For tendon injuries, and appropriate strength program, combined with avoiding tendon compression, and a graduated return to sport, works well to improve function in most cases

For joint osteoarthritis, many people will get significant benefit from interventions such as strength exercises, footwear modification, weight management and bracing.

Unfortunately this joint disease isn’t reversible, although the symptoms can be minimised by the above interventions.

There is new research looking at stem cell injections for knee osteoarthritis – again this is unproven at this stage.

These treatments are by and large not ‘sexy’ or exciting, and don’t promise the idea of a ‘quick fix’ – which may explain the popularity of PRP currently.

The take home message is that if you are offered PRP by your treating physio/doctor/surgeon – consider it very carefully.

It may be an appropriate trial intervention if you’ve exhausted most other conservative methods and are looking for an option to avoid surgery.

However there are few other situations in my opinion when these injections can be justified.

Addendum (March, 2019)

Almost five years have passed since I first wrote this article and it’s generated a few comments, so time for an update.

Apologies for delays in replying as I hadn’t been receiving notifications on this blog.

So what’s changed in the last five years?

• PRP for tendons is even less in favour than it was in 2014 – Some studies have shown benefit for PRP compared to steroid injection (gluteal tendon mainly) although these need to be interpreted with caution as steroid is thought to be detrimental to tendon structure. A trial with an inert substance (e.g. saline) would give more information.
• PRP for joint pain (osteoarthritis) is more in vogue – Some trials have shown benefit for PRP for knee osteoarthritis for up to 12 months when compared to hyaluronic acid (e.g. Synvisc) or saline. This is good news! The review article is here. So PRP may be an option for knee joint osteoarthritis in addition to other treatments (strengthening, load management, education, medication etc.).
• PRP for ligament and muscle injuries hasn’t come too far – there are no high quality trials of which I am are that show benefit for these injuries. There is a systematic review showing no benefit for PRP for acute muscle injuries.