Funny because people who have had injury problems when given the right footwear have seen those problems reduced, a lot depends on the person, their weight and the feet.
And people who have had injury problems have also seen those problems reduced when continuing with the same footwear.
Neither event is notable if you don't have control groups of an appropriate sample size.
Contains links to a couple relevant studies: http://well.blogs.nytimes.com/2010/07/21/phys-ed-do-certain-types-of-sneakers-prevent-injuries/