I am VERY lucky because I have had very few injuries. Only one required that I go to a doctor to get some peace of mind. I run one rural roads in Pa with very severe slants on them for drainage. As a result my right hip started to hurt. I went to my usual running injury books and tried different shoes, less milage, heat, ice and advil. It was much better but not perfect so I ran on the other side of the roads. That did work but was not safe up on these roads. This was about a 3 month trail and error exploration.
So I decided to see a doctor to be sure I was not doing myself more damage and I also decided that running was the most important thing. So if I had to cut down on milage and not do marathons I was prepared to do that. The doctor found nothing wrong and suggested that I run on roads that were not slanted at all.
So that meant that I would be always doing hills up here. The only flat roads were in the middle on the rural routes ( difinitely not safe) or run on the side roads. All side roads up in our village are up the side of a mountain. Now I know why they call where our house is the FLATS. So for about a year I have been on hills, but flat, and I am doing fine. Once in a while the hip hurts but it is very managable.