flat feet | Notion

Normal development

Flat feet are part of normal variation and usually do not reflect underlying pathology
At birth all feet are flat, as we begin to walk and the muscles develop the arch will also develop
Some children continue to have flat feet which persist into adulthood without any functional problem

Can be a normal variation affecting up to 20% of the population where the medial arch does not develop in childhood
May have a familial tendency
Patients with generalised ligamentous laxity are more likely to have flat feet
Acquired flat foot may be due to tibialis posterior tendon stretch or rupture, rheumatoid arthritis or diabetes with Charcot foot (neuropathic joint destruction)

Mobile/flexible flat feet are those where the flattened medial arch forms with dorsiflexion of the great toe (Jack test)/form an arch when patient tip-toes
Flexible flat footedness may be related to ligamentous laxity, may be familial or may be idiopathic
The flat footedness may only be dynamic (present on weight bearing only)
Flexible flat‐footedness in children is a normal variant and medial arch support orthoses are not required
In adults mobile flat foot may be related to tibialis posterior tendon dysfunction

In the rigid type of flat footedness the arch remains flat regardless of load or great toe dorsiflexion
This implies there is an underlying bony abnormality (tarsal coalition ****where the bones of the hindfoot have an abnormal bony or cartilaginous connection) which may require surgery
May also represent an underlying inflammatory disorder or a neurological disorder