This concept was discovered by Dr. Brian A. Rothbart, DPM, PhD through studying the motion of the foot to fully understand the root cause of over-pronation and how it impacts the body in motion. Noting that the first metatarsal and big toe was elevated when the foot was close to its optimal functional position, he investigated clinical literature published on the development of the fetus as well as studies done on cadavers to learn of an anatomical (structural) variation in the head of the talus (ankle bone) that seemed to explain this behavior.
It was discovered that over-pronation seems not to be caused by “fallen arches”, but rather by this anatomical variance of the talus. The head of the talus (lower forward portion of the ankle bone) controls the geometry of the first ray (first metatarsal and big toe). A congenital development causes the first ray to be elevated so that the foot rolls in when weight is shifted to the mid and forefoot.
Dr. Rothbart also came to question the logic of just building the ground up under the foot to support it. That was in fact his first approach, but he noticed this idea was not workable because in nearly 100 % of the cases, he ended up over compensating the patient. Through persistent work, he discovered that he only needed to build the ground up approximately one third of the way causing the first metatarsal and the big toe to have ground contact slightly earlier in the gait cycle. This timing change in ground contact appears to cause a proprioceptive response of the muscles controlling the medial column of the foot, causing a significant reduction in dynamic over-pronation.
