The main model that the use of foot orthotics in the use of patellofemoral pain is based on is that excessive pronation (‘overpronation’) of the foot causes excessive internal rotation of the tibia which cause malignment of the knee and this results in symptoms that usually gets called patellofemoral pain syndrome. However, while this model is widely applied in clinical practice, the research that supports it is poor and more often than not, actually contradicts the model.
However, several studies that use foot orthotics for patellofemoral pain in runners have shown that they can help. Because of that, it now appears that the model that is used to rationalize the use of foot orthotics is wrong, but if you do use foot orthotics based on that model clinically, then they do appear to help. This is paradox that can be used to criticize the use of foot orthotics. It has been suggested that the foot orthotics can help for other reasons than just trying to stop the ‘overpronation’ and simply reduces the forces or loads in the kinetic system.