Can platelet rich plasma injection eventually replace knee replacement surgery?

No: Platelet rich plasma (prp) contains components of blood important for soft tissue healing, but it lacks the pluripotential healing characteristics of stem cells. Will stem cells someday replace knee replacements? If we can find out a way to reverse the arthritic sclerosis of bone, break down the cartilage matrix, and ramp up the cellular division of chondrocytes, then yes. Its one step at a time.

Unlikely: There currently is no evidence that this treatment can reverse the damage seen in severe arthritis.