In another study in 1996 physiatrists (doctors in physical medicine and rehabilitation) at the Mayo Clinic the doctors were much less likely to recommend a person not go back to sports that included high or moderate impact. Both studies showed the difference in physician recommendation to their patients and also the expectations of the ability of the implanted joint to perform under high stress situations. In other studies the effect of high and moderate impact sports has been shown to be deleterious on the longevity of the knee replacement joints.
Although the pain you felt before the surgery has been eradicated the mechanical limitations of the replaced metal and plastic knee don’t hold up to the impact of running with knee replacement. The bottom line is that the replacement isn’t as durable as the original equipment.