Podiatry focuses in the disorders of the foot, ankle and lower extremity. Thus, Podiatrists do not usually address knee, back or neck pain. However, there is a Principle in biomechanics which can be referred to as the Kinetic Chain. The Kinetic Chain is an engineering concept for analysing human movement and a foundation of rehabilitation medicine.
There is the Open Chain and the Closed Chain. The Closed Chain is defined as one end being fixed in space and does not move. This obviously applies to the leg during gait, which remains in constant contact with the ground which is an immobile surface.
If we think of the human musculoskeletal system as a single chain, we can see how a dysfunction occurring at the foot, that is the end which is in contact with the ground, can propagate a domino effect all the way up to the head. This is where it brings us to the knee, back, and neck, as it relates to the problems occurring at the feet.
One common example our Podiatrists regularly see in Singapore is what happens when a person’s foot pronates or flattens.
When the foot pronates, the first thing that happens to the leg is it internally rotates. This sets up a torque at the knee joint which is not meant to rotate in that direction. This causes joint damage in the long term, leading up to knee replacement surgeries.
The next joint affected is the hip. Not necessarily hip pain, but the spine compensates for any abnormal alignment or positioning of the hip, and low back fatigue or pain is the result.
The neck, which is the cervical spine, is at the end of the kinetic chain. Pain from the distal influence of the feet is less likely than with knee pain, but it can happen. For example, leg length difference over time will abnormally curve the entire spine.
The feet are similar to the roots of a tree; what happens down at the ground changes everything above it. Therefore, Podiatrist-prescribed Orthotics can correct malalignment from the bottom up and improperly-made insoles or footwear can cause malalignment where there was none, and cause damage where there should not be.