the joint surface of the talus represents a laterally based cone segment

The foot is connected to the leg in the ankle joint. The ankle joint is a single-axle hinge-joint. Its motion axis is essentially a straight line connecting the peaks of the medial and lateral malleus.

Its movements are the dorsal- and plantar flexion.

The motion axis of the ankle joint forms an angle of 80 with the horizontal plane and 15 to 20 with the frontal plane.

The joint surface of the talus represents a laterally based cone segment.

Due to its form and position, the single axle joint brings the foot into ab-adduction during its movement and at the same time ensures a small rotation of the leg above the fixed foot.

What is the foot?

The foot is that what is inside the shoe.

The human foot is a race-specific functional unit consisting of 26 bones.

Why is the foot so special and important?

1. In the human evolution it is the youngest race-specific structure.

2. The kinetic chain of the lower extremity becomes closed kinetic chain due to the support of foot on the ground.

3. The foot is the key of absorbing the rotation.

The foot is the youngest part of the human organism that developed about two million years ago. Atavistic marks can still often observed.

According to the convention, the foot is a dual arched structure supported on three points.

Statically the arched structure is the most suitable one for load bearing purposes where the load bearing capacity changes in proportion to the height of it.

The arched joining of the metatarsal bases to the tarsus forms the transversal arch that is higher in proximally, its peak is the basis of metatarsus II while the heads are in a single plane.

Due to their flexion, the metatarsals also forming of the longitudinal arch as well.

What supports the arch?

Is it a tension wire or support of its two ends?

What is the function of short sole muscles?

In general the contraction of the muscles are drawing together their origin and insertion, and due to their attachment to the bones forming joints cause movement around the motional axis.

In case of the short flexors with the origin at the calcaneus and insertion at the medial phalanx the contraction results in the plantar flexion of the lesser toes.

The axial load tends to break the end- points of the arch open. The short sole muscles, however, do not connect the points A and B together, instead, they are attached to the medial phalanx.

Thus, the real mechanical tension is resulted not by the active contraction of the short flexors, rather the passive extension that is the dorsiflexion of the toes

The importance of the short sole muscles due to the flexion of toes is the cooperation in load bearing and stability during the toe-off; however, they play no part in maintaining the arch of the foot.

The foot can be statically modeled by means of a simple lattice structure built of triangles.

As the triangle preserves its form in spite of any load affecting at its nodes, the structure fails to collapse under any load.

The existence of the arch is only a necessary but not sufficient condition for the normal function of the foot.

What is the function of the foot?

The tasks imposed on to the foot in static and dynamic conditions are as follows:

1. It is a basis bearing the body weight that shall lye on the ground to ensure the proper stability in case of either double- or single-foot support.

2. While walking at the heel-strike the foot has to be springy to damp the abrupt load caused by body weight.

3. The axial rotation that occurs around the longitudinal axis of the lower extremity during gait has to be absorbed.

4. It shall be appropriately flexible to reduce the amplitude of motion of the gravitational centre and the kinetic energy necessary for its displacement to as low as possible.

5. It shall be appropriately rigid in order to be capable of functioning as a lever in forwarding the body weight.

Due to its special structure, the foot is capable of fulfilling all these tasks

In itself, a rigid arched structure would result in an appropriately stable static formation; on the other hand, the foot is a dynamic functional unit the normal function of which is essential during gait.

Human GAIT

The human gait is a specific and individual way of voluntary displacement motion.

In respect of consciousness, it is a secondary automatism, that is, a learnt process except the simultaneous movement of the arms.

The gait typical to adults is developing in childhood between 7 and 9 years.

The gait is as typical to the individuals as the mimetic and gesticulation.

In addition to individual characteristics, momentarily external and internal circumstances, e.g. disposition, tiredness, cloth, weather- and road conditions are also reflected in the gait.

There are, however, well definable permanent parameters that promote to compare the various types of the gait, and the pathologic gait from normal one to be distinguished.

Why is the gait of outstanding importance?

– The regeneration stimulus is the own function of each tissue: load of bones, contraction of muscles, pressure (variation) of cartilage. /Egyed Béla/

– Self-dependent displacement FREEDOM

How can be determined the normal gait?

The gait consists in the translocation of the gravity centre of body from one point to another one through continuous losing and recovering the equilibrium by means of cyclic plantigrad alternating bipedal motion

The gait consists in the translocation of the gravity centre of body from one point to another one through continuous losing and recovering the equilibrium by beans of cyclic plantigrad alternating bipedal motion.

Mechanically it means the displacement of the mass of body within a step length that involves work to perform.

It is known from the mechanics that, if a mass is in a steady motion on a straight line without the influence of any external force (including reactive force), the energetic situation is the same as if the mass were in standstill. It could occur if we were rolling on two wheels

The bipedal gait also involves the necessary rhythmical motion of the gravitational centre both in vertical and lateral directions.

When the body weight is transferred from the one foot to the another one, that is, the lower extremities are separated, the distance between the centre of gravity at the height of the sacrum and the ground is smaller than that if the trunk passes over the relatively extended lower extremity. This results in rhythmical vertical oscillation during gait.

Thus, the centre of gravity moves along a sinusoidal curve in the vertical plane and reaches its maximum height immediately after passing over the load bearing lower extremity; then, it moves downwards. It reaches its deepest point at the time the heel contact of the opposite lower extremity; then, it moves upwards again.

The amplitude of the curve lies between 4 and 5 cm as an average.

During gait, the body fails to remain in the plane of motion; instead, it oscillates laterally, while making effort to preserve the centre of gravity approximately above the load bearing lower extremity.

The lateral translocation follows an oblique sinusoidal path of 4 to 5 cm amplitude.

The gait consists in the translocation of the gravity centre of body from one point to another one through continuous losing and recovering the equilibrium by means of cyclic plantigrad alternating bipedal motion.

Positions of equilibrium:•stable•unstable•ndifferent

The equilibrium is stable if it tends to restored in case of small deviation

It is unstable if, in case of any small deviation, the equilibrium is disturbed.

Indifferent: the equilibrium is independent of the extent of deviation.

Human standing on two legs is in stable equlibrium.

During gait, as the lower extremity swinging forward leaves the ground, the centre of gravity lies in front of the supporting surface and the body tends towards the state of losing the equilibrium until the heel of the lower extremity contacts the ground.

When the opposite lower extremity pushes off and swings forward, the center of gravity becomes behind the supporting surface that represents an unstable position again. As the swinging extremity passes by the side of the opposite lower extremity, the centre of gravity moves forward again. Thus, the centre of gravity of the body proceeds forward while losing and recovering the equilibrium repeatedly.

The gait cycle represents the section between two heel contacts on the same side.

The gait cycle consists of a stance phase and a swing phase.

The load bearing period i.e. the stance phase passes 60% of the whole cycle while the swing phase passes 40%.

In case of normal gait, the cycle time of movement amounts to 1000 ms as an average (850 to 2200 ms).

The average time of stance phase is between 670 and 720 msec.

The sections of standing phase are:

• initial contact (normally = heel contact)• full flat period• midstance• heel off• maximum load of the fore-foot ( the row of the

MTP)• toe off

The swing- phase starts with the toe off, the three sections of which are

- acceleration

- middle swinging section

- deceleration.

Under normal circumstances, the gait cycles follow each other periodically shifted by a half-period on the opposite side.

The state when the rhythm of the gait is disturbed, that is the motion cycles of the two lower extremities are different is called limp.

The gait is pathologic, if the motion cycle differs from the normal one at both side.

The gait consists in the translocation of the gravity centre of body from one point to another one through continuous losing and recovering the equilibrium by means of cyclic plantigrad alternating bipedal motion

The human gait as a structurally determined function is an admirably complex process unparalleled in the living world.

Walking on sole and with two feet i.e. the plantigrad bipedalism is characteristic exclusively for human beings.

The human bipedalism can be biomechanically explained: basically the form of the tarsus being the tarsal bones above each other resulting in the arched structure of foot and the position of the first radius

The race-specific structural development of the human foot is not a consequence, instead, it is a condition of setting on two legs and the upright posture during the evolution.


Alternating bipedal motion = the two lower extremities move alternatively.

In case of alternating bipedal gait, the separation of the lower extremities necessarily originate the rotation of the pelvis in the horizontal plane.

During gait, the axial rotation is a biomechanical necessity resulting from bipedalism.

During gait, the trunk, the pelvis and the lower extremity is rotated around a vertical axis in the horizontal plane. The direction of rotation varies in the different phases of gait. In the swing-phase, the lower extremity is rotated progressively in inward direction and, in the stance- phase – while the foot is fixed by the body weight on the ground — the direction of rotation is changed and outward rotation occurs until the toe-off..

The rotational axis of pelvis is the load bearing lower extremity, the movements of the hip joint will determine the distal rotations.

One of the most important functions of the foot is to absorb the axial rotation of the lower extremity during gait.

During the axial rotation, the lower leg makes turn around the talus fixed in the ankle joint as the key moves in the lock.

Due to the form of the joint surface of the talus, (lateral based cone segment) the movement in the ankle joint results in a sort of rotation as well, however, it is not enough to absorb the axial rotation that occurs during gait

The structure that allows or even absorbs the axial rotation of lower extremity above the fixed foot is the subtalar joint.

The motion axis of subtalar joint is an axis directed from the front-inside-above to backwards-outwards-downwards; the joint itself is a hinge joint of oblique axis composed of three joint surfaces.

The forefoot, however, shall be fit on the ground; that is, the foot shall be returned from its pronated or supinated position.

This takes place in the transversal-tarsal, or so called Chopart joint.

Based on its function, the motion axis of the subtalar joint represents a right-handed or left-handed screw.

The movement around the oblique axis of the subtalar joint means common rotation going with translation in the opposite direction of the calcaneus and the talus. Therefore, this can be modeled with a union nut.

The internal rotation of the tibia makes to turn the calcaneus in valgus position and translate to backward, the talus will turn inward and translates forward, thus the tarsus lengthened, and the forefoot turns to abduction and eversion.

In the stance- phase, before the heel-off, the direction of the rotation changed, and until the toe-off external rotation occurs.

During the external rotation of the lower extremity, the calcaneus turns to varus position and forward, the talus rotates externally, and slides backward making the tarsal complex shorten. At the same time, their frontal surfaces joining in the Chopart joint fail to remain parallel to each other; consequently, the common temporary joint axis is terminated and the tarsus is locked.

This mechanism can maintain the arch of the foot during the stance phase of the gait.

It is the m. tibialis posterior, that actively ensures adduction and supination of the forefoot in addition to the structurally determined function.

As a result of locking the tarsus, the foot become a rigid structure in the midstance, acting as a rigid elevator, which is necessary to transfer the body weight from the hind-foot to the forefoot during the heel-off.

After the toe off as the swing phase begins internal rotation occurs again, and the foot become flexible enough to contact the ground decreasing the shock.

In order to perform this structurally determined kinetic chain reaction correctly, the anatomic and functional soundness of the foot is necessary.

Postural failures of the foot: Snapped-up footForefoot adductusForefoot adduction with supinationForefoot abduction

Minor deformities on the forefoot: syndactylia, clino- and camptodactylia,

dig.V.varus-infraductus, „piano-key toes”, metatarsus primus brevis ( et adductus)

Congenital deformities of the foot: ClubfootTalus verticaleHypoplasia of the IV. Metatarsus (radius) Tarsal coalition

Congenital clubfoot

Pes equinovarus-metatarso-adductus is a 3D deformity of the foot. There is equinus in the ankle joint, the calcaneus is in varus position, the forefoot

is in adduction and supination, the tarsus is shortened, and locked.

A few years earlier the common treatment for the clubfoot meant serial casting with redressment and at the age of 1.5 or 2 years operation by Steindler et Kabanak.

Unfortunately, the results were poor, and even the motion in the ankle joint was restricted.

Ponseti technic

Nowadays the Ponseti technic offered instead. The main difference is first to open the locked tarsus, and than make a correction.

The foot of infant when can walk in itself

What kind of shoes should to wear in childhood? „Shall it fix the ankle”?

Painful leg in infancy

Going on tiptoe

Walking with internally rotated feet

Pain in the heel > Apophysitis calcanei

Different types of apophysitis at the foot: - Köhler I. - Köhler II. - os tibiale extern - Basis of the V.metatarsus - sesam-inflammation

Excavated foot

General characteristics are the abnormally high longitudinal arch, the calcaneo-varus and the hammer-like position of the toes. Pes excavates or cavo-varus is not a unified disease in respect of either its origin or clinical aspect.

By Sandifer:

A. IdiopathicB. B. Symptomatic – the deformity is an

outcome and not a progressive one

• Peroneal muscular atrophy (CMT= HMSN I. type)

• Friedrich ataxia• Myelodysplasia – spinal cord malformation

It is not necessary that excavated feet in itself cause complaint. Due to the steep position of calcaneus, however, the movements of both the ankle joint and the subtalar ones are restricted that result in instability of the foot in the course of time. In the rigid and progressive forms, however, the increased load at the basis of the V. metatarsus may lead to ulceration of the sole.

Flatfoot

What is the flat foot in childhood? Is it an illness or deformity?

Is it a state to be treated or a normal phase of development that will improve spontaneously?

The necessity of the treatment depends on the severity and of the consequences.

The flat-foot can result in

- functional insufficiency

- pes planus fixatus

In childhood the most typical clinical appearance of the flatfoot is the increased valgus position of the calcaneus.

In case of extremely increased calcaneovalgity the foot lost the ability to absorb the rotation resulting in increased and permanent external rotation during gait. This means the functional insufficiency of the foot.

The flat foot can be fixed and the foot becomes a rigid structure with lengthened tarsus and forefoot abduction.

The pes planovalgus can accept as a sort of dysplasia in the development of the foot acting as a functional unit.

The necessary and sufficient condition of the normal function is the normal structure and the proper function of the muscles of the lower leg.

Because of the consequences affecting the bony growth and the structure of the foot, the flatfoot in childhood has to be treated.

.

Physiotherapy or exercises? Corrective shoe or insole?

Does the insert waste the muscles or promotes the proper development of bones?

What is the role of short sole muscles?

The flat-foot in childhood corresponds to a growth disharmony of the foot where the incorrect way of development may lead to consequential dysfunction, deformity of the tarsus joints and, finally, the functional insufficiency of the foot.

As the alterations during the growth period can result in persisting deformities in the adult, it has to treat due to its possible consequences.

An appropriate conservative therapy of flatfoot in childhood is

- corrective shoe until 3 years- insole above 3 years- special physical exercises