Mechanism of Dysfunction
One of the main causes for the development of Flat foot, is the compromised of the alignment of certain key bones in the ankle and foot. There is a biomechanical compensatory phenomenon that occurs in the body as a response to misalignments and is the results of this compensatory mechanism that lead to the Flat foot deformities and many other foot abnormalities.
The lack of motion (hypomobility) caused by a dysfunctional misalignment ankle joint, creates a need for the body to make up for that loss of movement somewhere else, causing the adjoining foot joints to become more movable (hypermobility) to try to maintain the overall range of motion of the ankle and foot. In a short term, this compensatory mechanisms allows the foot to keep up with the biomechanical demands at the time but in a medium to long term, If the main ankle dysfunction is not resolved, the foot bones become extremely flexible and as a results enters in a pattern of dysfunction dropping down and compromising the arches.
Another important concept seen in the foot is the keystone biomechanical principle which allows the arches to be maintained in an architecture mechanical advantage providing one of the most beneficial and least energy support system in the body
A keystone is the wedge-shaped stone at the apex of an arch or typically round-shaped one at the apex of a vault. In both cases it is the final piece placed during construction and locks all the stones into position, allowing the arch or vault to bear weight.
There are 3 arches that made up the foot: Medial, Transverse and Lateral arch. The common sequence of dysfunction, begins with a misalignment of the Tibia-Talus (master bone of the foot) joint, creating a hypermobility of the navicular bone (Medial Arch stone bone) causing the inner arch to become compromised. The transverse arch is the next in the sequence to fail, due to the maintained hypermobility and over flexibility of the foot, the middle cuneiform (Transverse Arch stone bone) drops compromising the transvers arch which eventually cause to the lateral arch to fail by the hypermobility of the cuboid (Lateral arch stone bone) leading to a total flat foot deformity.
Clinical assessment to identify the key joint dysfunctions of the Ankle/Foot following by three set of X-ray analysis.
Anterior – Posterior (AP) X-ray ankle view is essential for proper diagnosing the master joint of the ankle (Tibia-Talus) as the origin of poor arch mechanics starts from a dysfunctional ankle joint.
Lateral Xray view is important to check the degree of the total arch compromised, specially the medial arch and its corresponding key arch stone, the navicular bone.
AP Xray foot view, aids to complete the total analysis of the transverse and lateral arches.
Specific adjustments of key bones of the ankle and foot (Talus, Navicular, Calcaneus and Cuboid) followed by a rehabilitation regime to strengthen the entire soft tissue support of the foot. In addition, tapping application and corrective orthotics may be needed as part of the early rehab program.
Depending on the chronicity and level of arch compromised a minimum of 6 weeks up to 12 weeks of treatment care may be necessary to resolve this deformity.