In order to walk, not only must our feet have the right hardware in the form of muscles, tendons, ligaments, bones, nerves, and energy supply cushioned by fat and wrapped in the tough outer covering of skin, but the brain has to have the exact software in the form of movement patterns for normal walking permanently implanted in neural network patterns.
And all the time the brain is also using sense organs such as the eyes to observe the outer terrain, then processing the information, comparing it with its current movement software program, and predicting the necessary adjustments to take into account the slipperiness, gradient and evenness of the terrain, the amount of buffeting by the wind, and the current speed of movement.
The ankle is adapted to absorb the forces involved in walking or running in an upright stance while still allowing us to move in any direction. It is a bit like a universal joint in a car that allows movement while still transmitting force.
When you walk your body develops a lot of vertical force, as well as the horizontal force that propels you forwards. You can easily see this if you get a friend to walk along a straight and level path in front of you, and observe the top of his/her head. You’ll notice that the top of the head goes up and down with each step.
This means that the total force acting through your ankle joint is sometimes greater than body weight, and sometimes less. The force of your body weight acting downwards and the force on your feet acting upwards meet in the ankle joint. If you add in sideways movements or uneven terrain, you can see that the ankle joint needs to be buttressed against large forces acting in many directions.
This buttressing is in the form of a medial ligament on the inside of the ankle; a lateral ligament on the outside of the ankle; a tibiofibular ligament binding the lower leg bones (tibia and fibula) together; and a large number of tendons flowing through the ankle to link the lower leg with the foot. You can’t see the ligaments easily, but you can see the tendons standing out as tense cords when you move your ankle.
All these muscles, tendons, and ligaments are important to your balance. As well as the visual feedback mentioned above, your ankle has a built-in feedback mechanism that helps maintain an upright stance. A rich supply of specialized nerves, called proprioceptors, are in and around the ankle, and these monitor the position of the ankle and send automatic signals, to the muscles to correct over-balancing.
Injuries to the ligaments of the ankle can destroy the proprioceptors and affect ankle function. Without automatic feedback you’d have to watch your ankles to see if they were being pushed outside their normal range of movement with the risk of damage. You just wouldn’t feel it happening.
One of the people I regularly exercise with had a long history of ankle injuries which has now restricted her involvement in the activities she loves. She had been spraining her ankles regularly while bushwalking for a number of years, without doing anything about it.
Now she has to wear an ankle strap, as so many proprioceptors have been destroyed that her ankle no longer makes automatic corrections when it is thrown off balance, and she rolls over on to the outside of her ankle without even realizing it.
Any damage to the ligaments of the ankle is serious, and should be taken seriously. Even a slight sprain should be strapped with a compression and elevated, and strapped with strapping tape tor the months that the injury takes to fully recover.
Without outside support, you’re likely to resprain the ankle, destroy more proprioceptors, lose more balance sense, and be more likely to sprain your ankle. A vicious cycle that can end up with an ankle that will dislocate with even normal walking.
The ankle must have strong and well-maintained supporting structures to absorb the forces involved in walking and running and must be able to use its in-built automatic gait-correction function to maintain a good foot-strike on the ground and an upright posture.