I was hit by a car at age six and my left femur was shattered. The way it was put back together shortened my leg a couple of inches. But, because I was only six year old, the left leg has now equalized with the right or at least they are very close. I had to wear one shoe with a huge heal on it which is probably what you would do with shims. A shim will go under your cleat so that when you are standing with your shoes on you will be standing up straight and both your hips joints will be the same distance to the floor.