Life is movement and movement is its essence.
„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.
MULTIPLE MEASUREMENTS
measurements per second
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
A joint, as you already know, is the connection of two bones through a system of ligaments. The ankle joint is a complex structure composed of several bones along with their corresponding soft tissues.
The ankle joint is divided into:
- The upper ankle joint (also known as the superior ankle joint), also referred to as the talocrural joint (commonly called the ankle), consists of the tibia, fibula, and talus.
- The lower ankle joint (also known as the inferior ankle joint), also referred to as the talocalcaneonavicular joint, is a compound joint that includes two main joints: the subtalar joint (calcaneotalar joint) and the transverse tarsal joint, also known as the Chopart joint.
THE UPPER ANKLE JOINT
The upper ankle joint (also known as the superior ankle joint), also referred to as the talocrural joint, is commonly called the ankle. It is made up of the ends of the tibia and fibula bones, as well as the upper part of the talus bone. This is a typical hinge joint: the talus bone is partially located in the bracket formed by the lower part of the tibia and fibula.
The upper ankle joint allows for movement of the foot upward (dorsiflexion) or downward (plantarflexion). When the foot is fixed on the ground, the joint enables the tilting of the shin forward and backward. The range of these movements depends on various factors, including the training of the foot, age, and the collagen content in the soft tissues surrounding the bones.
NEUTRAL POSITION
Neutral position is the natural position of the foot when you stand on the ground. There is an angle of 90° between the foot and the calf (except it is actually 0° and it is taken as a reference point for measurements for dorsal and plantar flexion expressed in degrees).
DORSIFLEXION
Dorsiflexion is the movement of the foot upwards towards the tibia. It is on average up to approx. 45°. In a normally functioning foot, dorsiflexion is inhibited by the tension of the posterior wall of the articular capsule and the calf muscles. Further more, the neck of the Talus eventually contacts the anterior edge of the articular surface of the tibia. It is referred to as "+" + the value of this movement. For example, "+ 15°" means the foot obtains 15° dorsiflexion.
PLANTARFLEXION
Plantarflexion is the movement of the foot downwards towards the ground and it is approximately 60°. In a normally functioning foot, plantarflexion is inhibited by the tension of the anterior wall of the joint capsule and the front muscles of the shin. In maximum deflection, the posterior process of the calcaneus rests against the posterior edge of the articular surface of the tibia. It is referred to as "-" + the value of this movement. For example, "-15°" means the foot has 15° plantarflexion.
THE ROLE OF THE ACHILLES TENDON IN THE DORSAL AND PLANTAR FLEXION MOVEMENT
The Achilles tendon, although not directly connected to the upper ankle joint, also plays a role in dorsiflexion and plantarflexion. Its elasticity affects the range of motion. This means that if the Achilles tendon is healthy and flexible, it does not restrict the movement of the foot upward or downward.
Unfortunately, in children with congenital clubfoot, the Achilles tendon is thick, shortened, and less elastic, making dorsiflexion nearly impossible. As a result, the foot remains in a strong plantarflexed position. The solution to this issue is a percutaneous Achilles tendon tenotomy.
THE LOWER ANKLE JOINT
The lower ankle joint (also known as the inferior ankle joint) is the talocalcaneonavicular joint, a complex, uniaxial, and rotational joint.
Anatomically, it consists of two separate joints, divided by the talocalcaneal ligament:
- Posterior ankle joint – the subtalar (talocalcaneal) joint
- Anterior ankle joint – the transverse tarsal joint, also known as the talocalcaneonavicular joint or Chopart’s joint
Functionally, these two joints operate as a single lower ankle joint. Due to its complex structure, the lower ankle joint enables all rotational and twisting movements of the foot. The combined action of the upper and lower ankle joints allows for a range of motion comparable to that of a ball-and-socket joint, even though it is not anatomically classified as one.
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:
INVERSION
Inversion is the movement of tarsal bone in which the undersurface of the bone moves towards the madian body plane. In inversion the lateral side of the foot touches the ground.
EVERSION
Eversion is the movement of tarsal bone in which undersurface of the bone moves outwards the madian body plane. In eversion, the medial side of foot touches the ground.
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.
NEUTRAL HEEL POSITION
Neutral heel position occurs when the heel is not deflected in any plane and receives the weight of the body with the entire surface of the calcaneal tuberosity. Both longitudinal arches of the foot are parallel to each other. The first and fifth metatarsal heads are evenly burdened, just as both sides of the foot (medial and lateral) rest evenly on the ground (the medial side has an arch, so it does not touch the ground with its entire length at the elevation).
HEEL VARUS
Heel varus is used for movements of inversion and adduction of the calcaneus. In this position, the calcaneus flexes slightly plantarlly, causing a slight adduction of the forefoot and elevation of the medial longitudinal arch. Cavus begins. The foot presses of the ground its lateral side.
HEEL VALGUS
Heel valgus is used for movements of eversion and abduction of the calcaneus. In this position, the calcaneus flexes slightly dorsally, causing the foot to slightly abduct and lower the medial longitudinal arch of the foot. The foot presses of the ground its medial side.
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:
NEUTRAL POSITION
The neutral position occurs when long axis of the foot is parallel to the imaginary axis of the body, dividing it into the right and left sides.
ADDUCTION
Adduction is that movement of a tarsal bone in which the distal part of this bone moves towards the median body plane.
ABDUCTION
Abduction is that movement of a tarsal bone in which the distal part of this bone moves outwards the median body plane.
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.
SUPINATION
Supination is a complex movement that occurs during the gait cycle. It is a natural movement which consists of inversion, plantar flexion and adduction. It occurs at the beginning of the gait cycle: first the floor touches the lateral side of the heel and the lateral side of the foot, just to do the opposite moments later. Supination gives the foot the stability it needs to balance. In supination, the calcaneus always moves into a varus position. If the foot is in supination, the lateral side of the foot is loaded more.
PRONATION
Pronation is a natural part of gait. It consists of eversion, dorsiflexion and abduction. It is the "middle" component of the gait cycle, in which the foot, after its first contact with the ground, rolls from the heel to the toe, leaning on the medial side to absorb shock by touching the terrain with a larger surface area than during supination. The foot is then very flexible and has great absorbent and adaptive properties. In pronation, the calcaneus always turns into a valgus position. If the foot is in pronation, the medial side of the foot is loaded more.
BLOCKED MOVEMENTS
Clubfoot is a three-dimensional deformity in which:
- the calcaneus is in inversion, varus, and plantar flexion due to a shortened 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 of the hindfoot 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 permanent and rigid, preventing any other movement and significantly limiting overall foot mobility
- the forefoot is in pronation relative to the hindfoot, which, with excessive use of stretching (redression) and plaster casts, may worsen the cavus deformity rather than correct it.
Blocking the head of the talus and abducting the forefoot in supination (its initial position) without touching the heel allows the trapped calcaneus to be released and prevents further deepening of the cavus deformity. Once the foot achieves its proper anatomical and functional alignment, the shortened Achilles tendon undergoes tenotomy, eliminating the final component of the deformity—the equinus position of the calcaneus (severe plantarflexion caused by the shortened Achilles tendon).
From my observations in the clinic and in the operating room, I realized that the orthopedists' failures in the treatment of clubfoot were relared, in part, to a poor understanding of the functional anatomy of the normal foot as well as of the clubfoot. Without this understanding, it is impossible to alter the forces that caused the deformity and apply the proper corrective manipulations and retaining casts.
- Ponseti I.V.: „Congenital Clubfoot. Fundamentals of treatment.” (2nd edition)
- Michaud T.: „Human locomotion”
- Earl J.: „Born to walk”
- Marciniak W. et al.: „Wiktora Degi Ortopedia i Rehabilitacja"
- Ghanem I. et al..: „Understanding the foot’s functional anatomy in physiological and pathological conditions: the calcaneopedal unit concept”
- Sensors
- Others: own