This is the study of mechanics in relation to the biological systems, in this case your body.
Biomechanics plays a large role in sports as it reduces sprins and frictions from misalignments but through these studies we have a greater understanding of how the mechanics of the foot relates to the whole body.
The foot mechanics are complex and vary with each individual. If the mechanics are misaligned then the leg position could be wrong putting undue pressure on the knees, hips and back. Repositioning the foot could help with multiple joint conditions including the foot itself
Repositioning is most often achieved with a insole made from a cast of your foot and manufactured in a laboratory to your prescription which is established from a specific measuring system. It is like a contact lens for your feet.