For the past 50 years, the theory set forth by Dr. Root on foot mechanics has been the accepted standard. Most medical professionals, when discussing or treating foot problems, will view the feet from Dr. Root’s perspective, often referred to as “Root’s Biomechanics.” Dr. Rothbart built a different model based on research conducted by Dr. Morton who documented the effect and prevalence of a short first metatarsal bone. Dr. Rothbart is credited with defining the third dimension of “Morton’s Foot Structure.”
Current foot orthotics are based on Root’s Biomechanics which describes the presence of a varum across the forefoot which according to Dr. Root causes a twist of the forefoot relative to the rearfoot. This varum is said to cause hyperpronation of the foot.
Hyperpronation is also attributed to a collapsing internal longitudinal arch. To support the arch, most prescribed orthotics incorporate arch supports. The collapsing arch is considered to be the source of a hypermobile heel, and for that reason, most traditional orthotics will also incorporate a heel cup or cradle to hold the heel in place.
Some orthotics also incorporate transverse arch supports and forefoot or rearfoot posts. When forefoot posts are used they will typically span two or more metatarsals.
The basic idea with current orthotics is to support the collapsing arch and control the motion of the heel thereby seeking to stabilize the foot and reduce hyperpronation.
Dr. Rothbart describes a foot, Rothbart's Foot Structure, where the first metatarsal is not only short, but rotated and elevated. The “varum” documented by Dr. Rothbart is limited to the first metatarsal and the big toe only and does not extend to the second metatarsal or beyond (Primus Metatarsus Elevatus). Measuring thousands of patients, Dr. Rothbart found that the big toe must travel a distance downward to become weight bearing. This causes the entire medial column of the foot to collapse including the ankles which are simply following the motion of the big toe and first metatarsal. This collapse of the medial column of the foot defines hyperpronation.
Rothbart's Foot Structure is found in over 80% of the population, and everyone who has a Morton’s Foot Structure also has Rotbart’s Foot Structure. Morton’s Foot is defined by a short first metatarsal bone and/or a deeper web space between the first and second toe than between the second and third toe.
The most common reason for using Posture Control Insoles™ is to overcome the effects hyperpronation inflicts on the whole body.