Almost certainly not. A flexible, painless flat foot in a child is a stage of normal growth rather than a problem to be corrected, and there is no good evidence that insoles change the shape the foot eventually takes. What is worth knowing is how to tell that kind of flat foot from the small number that do need a look.
How the arch develops
Almost every toddler has flat feet. Babies are born with a pad of fat under the arch, the ligaments are loose, and the muscles that hold the arch up have not yet been trained by years of walking. As a child grows the fat pad thins, the ligaments tighten and the arch appears, in most children by about eight to ten. Some never develop much of one and go through life with flexible flat feet that never trouble them. That pattern often runs in families, and a parent with flat feet who has never had a problem is a reasonable guide to what their child can expect.
Why insoles do not build an arch
Parents are regularly sold orthotics, special insoles or "corrective" shoes on the promise that they will train the foot into the right shape. A well-known study followed young children with flat feet for several years, some in corrective shoes and inserts and some in ordinary shoes, and the arches developed the same either way. An insole holds the foot in a position while it is worn; it does not change what the bones and ligaments do once it comes off.
That is why a flat foot that does not hurt does not need one, and why there is no reason to put a comfortable child into something uncomfortable for the sake of how the foot looks. Insoles have a place, but it is for comfort in a foot that aches, not for correction.
The test you can do at home
Ask your child to stand on tiptoe. In a flexible flat foot the arch appears as they rise and the heels swing inwards, which is the foot working exactly as it should. Lifting the big toe off the floor while standing does the same thing. Then look at them from behind while they stand normally: both heels should lean the same way, and you should see about the same number of toes on the outer side of each foot.
A foot where the arch does not appear on tiptoe, or where one heel leans out further than the other, is the one to have checked.
When flat feet in a child do need a look
Pain in the arch, the inner ankle or the heel, particularly if it stops them playing or comes on after ordinary activity rather than an unusually long day.
Stiffness: an arch that does not appear on tiptoe, or a foot that does not turn in and out freely.
One side only: a foot that is noticeably flatter than the other, or an arch that was there and has now dropped.
Tiring or avoiding: a child who asks to be carried, sits out of games or complains of aching legs more than you would expect.
A stiff, painful flat foot between about ten and fourteen. This is the age a tarsal coalition declares itself: a bridge of bone or cartilage joining two bones in the back of the foot, present from birth, which stiffens the foot as it hardens. It is diagnosed on X-ray and CT, and it is treatable.
A sore bump on the inner side of the foot in an active pre-teen or teenager, often an extra small bone beside the arch, known as an accessory navicular, that rubs on shoes and aches with sport.
What treatment looks like when it is needed
For a flexible flat foot that hurts, treatment is usually simple. A supportive shoe with a firm heel. An off-the-shelf insole for comfort, with custom orthotics kept for an unusual foot shape or a foot that has not settled. Calf stretching if the calf is tight, because a tight calf is one of the commonest reasons a flat foot becomes sore: it forces the arch to give way with every step. And exercises to strengthen the small muscles of the foot and the tendon that supports the arch.
Surgery has a small place. A coalition that has made a teenager's foot stiff and painful can be removed while the joint is still flexible, and where it has already caused arthritis a fusion is the more reliable option. All decisions made with the family over time, and surgical intervention is only for a small minority of the children who come through the door.
Key points
Almost all toddlers have flat feet; the arch usually appears by about eight to ten.
A flexible, painless flat foot needs no insoles, no special shoes and no treatment.
Insoles support a foot while they are worn; they do not change its eventual shape.
Have the foot looked at if it is painful, stiff, one-sided, tiring your child out, or becomes stiff and painful in the early teens.
Where treatment is needed it is usually shoes, a simple insole and exercises; surgery is for the few.
More detail. Want the full picture for children and adults? Flat Foot covers flexible and rigid flat feet, arches that drop in adulthood, how they are assessed and what treatment involves.
Ready to discuss your treatment options?
Book a consultation with Dr Janan Chandrananth to have your child's feet assessed if they are painful, stiff or flat on one side only. Most need nothing more than reassurance, and the few that need more are better found early.
