Platelet-rich plasma (PRP) is one of those innovations in orthopaedics which has always had huge potential. It is widely used for variety of different acute and chronic conditions, but unfortunately the evidence of efficacy is still very weak.
Fracture healing has been suggested as potential target for PRP. Recent review in the Injury journal quite clearly states:
Based on current literature, the routine use of PRP to improve fracture healing cannot be recommended.
I highly doubt that this conclusion will change any time soon.
Another similar modality without any potential benefit to induce fracture healing has been low-intensity pulsed ultrasound (LIPUS).
Until further evidence rises, we should just accept that influencing natures own disease processes is very hard.