Clinical typology of the foot according to Merton L. Root, and correct position of the ankle

Most people know that flat feet are highly arched or normal. But not many people know what lies behind the term clinical or also functional typology and what benefit it has for the solution for deformities (permanent change in the shape) of the foot. Can some types of the feet affect the performance of the walk? Can a certain type of the foot have an effect on the formation of the problems in the musculoskeletal system such as bunion or even pain in the lumbar spine or migraines? I have dealt with these questions as well as with other questions in my thesis, which i would like to present to you.

American podiatrist Merton Louis Root (1922-2002) dealt with the problems of feet and their deformities already during his studies, in the 50’s and 60’s he started to observe feet from a completely opposite perspective than his counterparts. He was a “pioneer”, who saw the feet not as a one static part of the leg, which serves as a basis for the whole body, but as

a very complexive, dynamic structure able of many small, but very important movements, which in result enable the movement from one place to another, such as walking and running.


According to this knowledge about biomechanics (mechanics applied to the movement of human body) and kinesiology (study of movement), he divided the foot into four types, according to the position of the forefoot and back foot against each other:

  • Deflecting back foot - heel bone is rotated, and standing on the inner edge
  • Deflecting forefoot - heel bone is in one line, but the forefoot is rotated through the big toe upwards
  • Deflecting forefoot - heel bone is in one line, but the forefoot is rotated through the pinky toe upwards
  • Normal type of foot - heel bone is in straight line with forefoot

These types of feet (deformities) as Root named them, have a significant and especially negative effect on the position of the joints of the legs and basically also position of the spine. Based on this new typology Root composed a concept of functional and compensating orthotics (heel pad, forefoot pad, etc), with which he compensated negative effects by the individual types of the feet and other joints on the other joints.

Deflecting back foot (during unburdened leg and when standing)


Heel bone is rotated, standing on the outer edge. In a standing position the ankle joint (subtalar joint) significantly turn inside, in order for the whole foot to get into contact with the ground.

Deflecting forefoot (during unburdened leg and when standing)


Heel bone is in a straight line, but the forefoot is rotated through the big toe upwards. In a standing position the ankle joint (subtalar joint) has to compensate and turn inside, in order for the forefoot to get into contact with the ground.

Forefoot valgus (during unburdened leg and when standing)


Heel bone is in a straight line, but the forefoot is rotated through the pinky toe upwards. In a standing position the ankle joint (subtalar joint) has to turn outside, in order for the forefoot to get into contact with the ground.

Even though his new concept was very advanced, it also met with a great criticism in the scientific circles. Determining the foot type according to Root is to a certain degree subjective, as it is by most clinical examinations, where the diagnosis depends on the doctor, his experience and observation. This concept is widespread in the western world, used since it was found, it was developed and still is developing in accordance with the latest findings from the research. Even though that some of Root’s terms are not easily testable by science, it is still the most sophisticated system of foot typology with compensating orthotics (heel pads, forefoot pads, etc.). In Czech republic this concept is not very used. Therefore it was one of the goals of this thesis to re-introduce this concept.



The thesis was named „The effect of clinical type of the foot on a kinematic parameter of walking”. Simply said we observed whether the individual type of feet have some effect on the performance of walking in individual joints of the legs (ankle, knee, hip joints and pelvis) by young healthy males. Kinematic parameters included the size of the angle of movement in the joints in all three rows. We used for evaluation kinematic 3D analysis, during which six infrared cameras scanned the walking person and also recorded the movement in the joints (the degree of the angle during bending, rotation, straightening), on which were placed reflexive points. After processing the datas and evaluation we came to a result that every type of the foot has its certain negative effects on at least one joint of the lower leg and pelvis and it affects walking in individual joints of the leg.
Video kinematic depiction of a person during walking - view from the side

The results showed that all three functional types of the leg have some influence on the kinematic parameters of the pelvis during the stepping cycle. The position of the pelvis was mostly influenced by the the deflecting forefoot, namely the anteversion/retroversion of the pelvis (tilting the pelvis forward and backwards).
Deflecting forefoot and back foot have a significant influence on the hip joint during walking especially during rotation and adduction/abduction (movement to the sides). During walking, the knee has to deal with rotation due to deflecting forefoot and back foot. The valgus deformity of the forefoot and deflecting forefoot have an effect on the kinematic parameters of the ankle joint during walking, especially on the dorsal flexion and plantar flexion. The most significant effect has the type of deflecting forefoot, on all joints of the legs and the pelvis. In addition by this type of foot, there is insufficient dampening of the impacts of the foot hitting the ground, which leads to formation of bunion, stress fractures of the metatarsal bones, inflammations from the overload, micro ruptures and complete torn of the Achilles tendon, valgus knees (knees in a “X” shape), knee pain, similar symptoms as by the pressure of the spinal cord root L5 and more. Therefore it has various negative effects on the musculoskeletal system.

Unfortunately in our common medical experience we rarely meet with a professional, who would be able to diagnose the patient according to Root's method, and could recommend based on that the correct type of orthopedic compensating support. For now, it is good to know about this option and ask about it, it will increase the interest about this method among doctors and public, and after some time it may be used and applied by us as well.

Author:  FYZIOklinika physiotherapy Ltd., Prague, Czech Republic
Source: Web

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