A complex and sophisticated interaction of bones, ligaments, muscles and nerves within and above the foot defines its anatomy and function. Anything that interrupts the integrity of these structures leading to a collapsed arch can cause symptomatic flat feet.
Examination of the foot begins with an examination of the entire child, because the flat foot may have an underlying cause. Common disorders causing symptomatic flat foot include: cerebral palsy, some forms of muscular dystrophy, juvenile arthritis, inherited disorders affecting the nervous system, and some connective tissue disorders.
Flat foot can also originate from unusual anatomy such as a tarsal coalition (bones joined together), ligament or muscle damage, restricted ankle movement, outward rotated lower legs, and knock knees (where the legs bow inwards at the knee).
Obesity can result in collapse of the arches by the increased load on the foot. If knock knees also develop, the middle of the foot will tend to turn out (abduct). The foot will point outwards when walking, instead of straight ahead, which is inefficient and can cause early fatigue.
Footwear in early childhood has been thought to cause flat foot. Recent research questions this theory, as populations that habitually walk barefoot have flatter arches than populations that wear shoes. It is likely that children who wear shoes, are not physically active and have flat feet will have decreased muscle activation in their feet and thus impaired foot function and weakness.
Some older children and adolescents develop flat feet in the absence of any disorder or associated factors. Understanding the role of the small foot muscles in stabilising the arch and promoting normal function of the foot and entire lower extremity might hold the answer. Though not customized to an individual foot, support insoles come in different models and profiles to suit most foot shapes or footwear types.