The same is true of AD. The way he runs does tend to lean him towards getting dinged up in games and a shorter career. Luckily he's still very effective. I wouldn't want him to change his running style just to get more years of service out of him. You let the players do what they do best, the way they do it & don't try to handcuff them.
With Harvin too, there was that hole thru the bone in his foot that many thought would cause him to break it quite easily, but that thus far has been a non-issue too that I think many forgot about.