We normally post articles about specific pathologies or cases of biomechanical abnormalities. This time, we wanted to take a step back and remind ourselves, and our readers, of just how amazing and wondrous our feet really are.
In our lifetime, our feet cover a distance of roughly four times around the world- that’s about 160,000 kms, or 100,000 miles! Each foot contains 26 bones, 33 joints, and over 100 muscles, tendons and ligaments. This complex structure is precisely and intricately designed to absorb shock and propel you forward through the world.
The skin on the bottom of your feet is the thickest skin found on your body. In addition to offering protection, this section of skin is highly sensitive, containing as many as 200,000 nerve endings. These nerve endings send important information to your brain about your surroundings. This information helps your muscles and joints adapt to the different terrains and environment and the challenges they pose.
At the foundation of the kinetic chain, your feet play a crucial role in what happens to the links above- ankles, knees, hips, spine, etc. A problem with your feet can lead to problems further up. Conversely, improving those foot problems can often improve problems experiences in other areas of the body, such as back pain.
One of the most important functions of the feet is to absorb shock. Every time you strike the ground during gait, the entire weight and force of your body is placed on these two relatively small sections, so this function is essential. To accomplish such a feat, the foot must be able to adapt intuitively to various terrains, flat or angles, smooth or bumpy, firm or yielding. This is the job of the arch, the joints, and the uniquely elastic plantar fascia within in. The subtalar joint between the talus and the calcaneus goes into pronation upon contact, which unlocks the foot and allows the bones to become loose and mobile. The arch flattens itself to enhance shock absorption and maintain stability.
Whether we choose to walk or to run through life, the other main function of the foot is propulsion. Loose and adaptive during stance and ground contact, the foot must become a rigid lever in order to actually get us going anywhere. In order to go from a loose to rigid, again the subtalar joint is tasked as the foot moves out of pronation and in the direction of supination. As the foot is brought back into its neutral position, the talus and calcaneus become locked into position, which in turn locks the midtarsal joint. Now the foot is rigid and can lift and move the body’s weight. In a normal foot, this entire sequence happens uninterrupted and on time. All the bones remain in their proper position and go through a minimal amount of motion. Consequently, no symptoms generally arise, and we are free to walk, run, skip, and dance without ever giving a second thought to the physiological ballet our body is performing.
Just a quick drive through biomechanics 101, and we are reminded of how complex our feet are, and how lucky most of us are to take them for granted. Along those lines, it is easy to fathom how these structures can succumb to the variety of pathologies that they do. Your role of foot specialist is an essential part of wellbeing for your patients, and should feel that much more fulfilling.