No detectable benefit: Study casts serious doubt on PRP injections

Platelet rich plasma injections offer no benefit in acute Achilles tendon rupture according to a large ‘robust’ evaluation carried out in UK hospitals.

The University of Oxford research team said the enthusiasm for the technique, made popular by its use in high-profile athletes, had got ahead of the clinical evidence on its effectiveness.

They also called for better evaluation of the technique – where the patients own blood is processed to produce a solution containing a high proportion of platelets before being reinjected – in other musculoskeletal conditions where it is being used.

Their trial looked at the effectiveness of the technique – in which PRP injections were given in the tendon gap within 12 days of injury – compared with placebo injections in 230 patients at 19 hospitals across the UK. Participants were randomised 1:1 to platelet rich plasma (n=114) or placebo (dry needle; n=116) injection.

To try and avoid problems seen in other research studies, the team took careful steps to ensure the PRP samples used in the procedure contained high levels of active platelets and leucocytes which released high concentrations of growth factors on injection. All participants received standard rehabilitation care (ankle immobilisation followed by physiotherapy).

There was no evidence that platelet rich plasma injections offered improvement on a range of measures including muscle tendon function, patient reported function, pain, goal attainment, or quality of life, the researchers reported in the BMJ.

The results show that despite a plausible hypothetical role for PRP injections in promoting faster healing and ‘encouraging’ laboratory studies showing benefits, in reality this “did not translate into a detectable patient benefit”.

Study leader Dr David Keene, an NIHR research fellow in the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences at the University of Oxford, explained that in the UK the procedure was predominantly used in private sports medicine, but it has started to be used within the public system as well, which had been their rationale for doing the trial.

In a paper in 2016, the team pointed out that despite 29 clinical trials of PRP in treating musculoskeletal soft tissue injuries it was unclear how effective it actually was because it was tested across a variety of musculoskeletal conditions, the studies were too small, or of poor quality.

“The idea is that you are trying to harness the body’s own mechanism to improve healing,” Dr Keene told the limbic.

“But what we found was no evidence that these injections improve a whole range of patient reported outcome measures as well as muscle recovery.”

He added: “The enthusiasm for the procedure has been ahead of the clinical trials.”

In an accompanying editorial in the BMJ, the researchers also pointed out that well-conducted clinical trials were particularly important for interventions such as PRP, which are not subjected to the same regulations as new medicines or even medical devices.

“It took years of development, trialling, and evaluation, to deliver this negative finding. Some may think that this was a misplaced effort and resources. But safety and efficacy are paramount as no intervention is without risk or cost, even if autologous.”

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