I don't know how prp compares to zynvisc 1, also an injection in the knee, but I had about 10 to 11 months of improved flexibility in my knees. A year later the surgeon said that we could repeat the process, however in my opinion this was a bandaid approach and we decided on the titanium knee replacement. What a difference.

At least it was not cortezone as this seems to deteriorate over time
Russell