A slight difference in length (3mm) can lead to pain over time. With inserts in your shoes, it can help with walking and running making sure the body is absorbing forces in a balanced way.
A leg length imbalance (anisomelia) can come from a torqued pelvis or an actual anatomical length discrepancy. An anatomical leg length discrepancy can appear with a shortened tibia, femur, or both. An over pronated foot can also cause a short leg in which a custom orthotic can easily fix. Knowing which type of imbalance you have is important, as the treatments are vastly different. A well trained chiropractor can easily spot the difference, which is not as easy as you might think. Sometimes there are combinations of a torqued pelvis and an anatomical difference.