When we are walking the range of movement needed at the ankle joint is really important. Once we put the foot on the ground the body above has to move forward above that foot. That forward motion occurs at the ankle joint, so it ought to be apparent that there ought to be nothing which prevents that forward movement at the ankle. Disorders such as arthritis in the ankle joint may affect that forward movement. Another frequent problem which could interfere with that forward motion are tight calf muscles. They stop the leg moving the necessary range of motion above the foot. In the event that motion is stopped than a number of compensations can occur. Firstly, walking is a lot harder. It is more tireing as far more efforts are required to walk. Secondly, your body has got to obtain that movement from somewhere. When it can’t get that motion at the ankle, then it could get it at the knee and when that occurs we then walk with a more flexed knee that is a hard way to walk. If the body does not compensate at the knee, then it gets the movement at the midfoot. If that occurs then the arch of the foot flattens and that can cause a variety of clinical problems.
For these reasons, doctors want to assess the flexibility at the ankle joint as part of a biomechanical assessment. There are numerous ways of doing this. One of the ways is a non-weightbearing examination with the foot and leg up in the air and the feet are just moved on the lower limb and the range of motion is assessed. Another, perhaps better way, would be to do what is known as a lunge test. This is a weightbearing way of measuring the ankle joint range of flexibility and in that position it is usually a better representation of the reality of the way that we walk.