„MASTERPIECE OF ENGINEERING AND A WORK OF ART”

For better understanding of movements taking place in a foot it is best to read the article ANATOMY first. It will undoubtedly help you grasp the construction of a human foot. Because of your feet you can stand, walk, run, jump, ski, swim and do all sorts of activities. You touch the ground with them, feel the outlines and textures. All these things are possible thanks to 26 bones, which articulate in 33 joints reinforced with over 107 tendons and ligaments. They are moved by numerous muscles that work together  in an amazing harmony to adapt to changing circumstances.  Your foot will react differently depending on whether you’re walking on ice, or chasing a ball on a dense tennis court. When you jump- it adjusts and when you ski or skate- it does the same. It will work differently in all those scenarios. Regardless of the type of activity you’re attempting, it is all possible because of the mobility in joints of a foot. Joints are junctions of bones,  that are connected to ligaments or tendons. They are protected by synovial capsules and synovial fluid and they can be moved by specific muscles.

MOVEMENT – MOBILITY AND GONIOMETER

When the muscles contract and release, their tendons move the bones they’re attached to and these bones move other bones linked to them via ligaments. This is just a summary of this complex mechanism. Movement is a very complicated process. This summary shows, that all the structures must collaborate, as they are communicating vessels: moving one moves the rest. Mobility is a feature of a foot, which is easily explained  as ability to move. The range of motion (ROM) varies and is determined by the joints (their construction).

RANGE OF MOTION (ROM)

is a measurement of movement around a specific joint. Each joint can move in specific directions. The range of that movement is expressed in degrees. Range of motion for specific joints varies insignificantly depending on individual predisposition, age, gender. In general, ROM gets smaller as we age. Is ROM measured? Standard device used to measure ROM is called goniometer. It consists of two arms and a 0-360 scale. One arm is constant and shows 0 and the second one moves on the scale.

The reconstruction of movement in three-dimensional recording systems means recreating the spatial orientation of the body movement. This is equivalent to finding the turnovers for each bone, on the basis of the data taken from special markers. Medicine has been interested in this technology from the very beginning. It can be used to diagnose diseases, plan treatment and track what progress this treatment brings. Thanks to the recorded images, it is possible to determine the trajectories of movement of the patient’s body parts, compare these movement paths with the accepted norms and determine whether there are any deviations from the norm. This allows us to improve the treatment or rehabilitation plan.

Since movement occurs in the joints, any soft structures involved in it can be both an aid and a restriction, reducing the range of motion or blocking motion altogether. In congenital clubfoot, there is a strong limitation of mobility (the range of motion is small or absent) due to a defect in the soft tissues, which causes problems with the alignment of the bones in relation to each other. The defect affects soft structures: ligaments, tendons, muscles. In them, a number of abnormalities appear, causing their pathology: shortening, calcification, fibrosis, which directly  influences the bone structures, shifted  relative to each other and slightly deformed. The pulling force of soft tissues is so great that it moves some bones relative to each other in certain directions.

MOTION IN THE ANKLE JOINT

Basically a joint, as you already know, is a connection of two bones with each other through a system of ligaments. The ankle joint is a complex structure consisting of many bones and soft tissues. The ankle joint is divided into:

• ankles mortise, also known as the talocrural joint (colloquially: ankle);
• ankles tarsus, otherwise known as the talocalcaneonavicular joint, is a complex, uniaxial, rotary joint.

ANKLES MORTISE

The ankles mortise otherwise known as the talocrural joint and colloquially as the ankle. It is composed of the ends of the tibia and fibula and the upper part of the talus bone. This is a typical hinge joint: the talus bone is partially located in the fork formed by the lower part of the tibia and fibula. The ankles mortise allows MOVEMENT OF THE FOOT UP (DORSIFLEXION) or DOWN (PLANTARFLEXION). While locking the foot on the ground, the joint allows the shin to tilt forward and backward. The range of these movements depends on many things: the training of the foot, age, collagen content in the soft tissues surrounding the bones.

THE ROLE OF THE ACHILLES TENDON IN THE DORSAL AND PLANTAR FLEXION MOVEMENT

The Achilles tendon, which is not directly related to the upper ankle joint, also contributes to the dorsiflexion and plantarflexion: its flexibility influences the range of motion performed. This means that if the Achilles tendon is fine and flexible, it will not restrict the upward and downward movement of the foot. Unfortunately, children with congenital clubfoot have thick, shortened and inflexible Achilles tendon, which makes dorsiflexion rather impossible. The foot is thus kept in a strong plantarflexion. The solution to this problem is the percutaneous Achilles tendon tenotomy.

ANKLES TARSUS

Ankles tarsus also known as the talocalcaneonavicular joint and is a complex, uniaxial, and pivot joint. Anatomically, two separate joints can be distinguished, devided by the talocalcaneal ligament:

• anterior ankle joint
• posterior ankle joint

Functionally they constitute one ankles tarsus. Due to its advanced structure, the ankles tarsus enables all rotational and torsional movements of the foot. The arrangement of these two joints: the ankles mortise and tarsus, gives the ankle the functional capabilities (freedom of movement) of the spherical joint, although in fact it is not.

POSTERIOR ANKLE JOINT

It is placed between the upper surface of the calcaneus and the lower surface of the talus bone. The main ligament of the joint is the talocalcaneal interosseous ligament. There are two movements in this joint:

This joint also allows for various “variants” of positioning the heel relative to the ground, when standing, that is when the heel is fixed (locked) and weighted down. This applies to its three positions relative to the longitudinal axis of the foot, i.e. the axis running parallel to the ground.

ANTERIOR ANKLE JOINT (talonavicular joint)

It is placed between the anterior part (head) of talus and the concave surface of the navicular bone. It allows torsion:

Everything seems relatively simple, if not for the fact that the foot has much greater mobility. These are linked movements. This means that one bone moves another one thanks to a system of ligaments, tendons and muscles. And this is how the foot can move in three planes, which you most likely are unaware of. Walking is the first stage in which the three-dimensional movement of the foot manifests itself. If you record your walk, slow it down and play it back almost frame by frame, it will turn out that your gait consists of many stages and each of them is necessary.

BLOCKED MOVEMENTS

Clubfoot is a three-dimensional deformity in which:

• the calcaneus is in inversion, varus, and plantar flexion (short Achilles tendon)
• the talus is medially displaced  – adducted and in severe plantar flexion, which causes the calcaneus to be blocked underneath
• there is a very strong supination with a big cavus, and it would be no wonder – supination is a natural part of the foot activity – were it not for the fact that supination is constant and stable, preventing any other movement, effectively  diminishing foots mobility.

Blocking the head of the talus and abducting the forefoot in supination (i.e. the original position) without touching the heel releases the blocked calcaneus and prevents deepening of the cavus. When the foot reaches its correct anatomical and functional function, the shortened Achilles tendon is subjected to tenotomy, which eliminates the last component of the defect – the equine position of the calcaneus (i.e. its strong plantar flexion caused by the Achilles tendon being too short).