There has been a study conducted in America which shows between 90% and 95% of Americans having a leg that is shorter than the other by more than 6mm. So does that mean that it is normal? No, that just means it is commonly seen.
So what does that mean? It means that the dominant leg are more prone to degenerative joint disease and osteoarthritis. That is why devices such are orthotics can be necessary depending on your case. With Chiropractic care, proper education can help with advising you what is needed