Parents very often will bring their children to a pediatric orthopedist’s office to have their feet checked when they believe their children are “walking on the inside of their feet” or their “arches have collapsed.” This common condition is referred to as a flatfoot or in orthopedic terms called pes planovalgus. Parents often expect that their child will be prescribed some type of special shoe or shoe insert to treat this condition. The following is an explanation of flatfeet.

Normally, a foot has several arches. They run across the foot transversally and along the foot longitudinally. All the foot’s arches are collapsed in a flatfoot but it is the collapse of the longitudinal arch which is most noticeable.

Flatfeet can be broadly divided into two groups; rigid and supple.

The rigid flatfoot is stiff, regardless of the position of the foot an arch will not be seen. This type of flatfoot is caused by some bony deformity of the foot and commonly leads to the development of foot pain or other problems.

A flexible flatfoot is supple. A longitudinal arch will be seen during some movements, such as standing on one’s toes. This type of flatfoot is caused by loose ligaments in the foot. Often these children are generally flexible. Flexible flatfeet rarely cause foot pain and rarely need treatment.

Flexible flatfeet are very common. Since almost one out of five adults have flexible flatfeet, it is better to think of flatfeet as a variation of normal foot position and not as a deformity.

Infants are normally born with flatfeet. The ligaments on the bottom of their feet do not tighten up enough until two years of age to be able to form a longitudinal arch in the foot. The development of this arch continues until approximately ten years of age.

In a flexible flatfoot, the longitudinal arch collapses with weight bearing because the ligaments on the bottom of the foot which hold up the arch are lax. The reason for this is unknown, although, flexible flatfeet do tend to run in families. The lax ligaments allow the bones of the hindfoot (back of the foot), especially the talus, to rotate out of their normal positions. The head of the talus rotates towards the inside of the foot and turns down. It is often felt as a bump on the inside of the foot where the arch should be.

The calcaneus (heel bone) rotates outward causing a child’s weight to pass inside the heel towards the floor when standing, making the foot a less stable base of support while standing. This outward rotation is demonstrated by the yellow line on the right image.

A flexible flatfoot is easily distinguished from a rigid flatfoot. The foot is supple in all planes of motion. When a child stands on his or her toes an arch will form on the bottom of the foot and the calcaneus will rotate inward because this foot position tightens the ligaments on the bottom of the foot. If a child is too small to stand on their toes, the same effect can be had by extending their first toe. If the foot is flexible, an arch will form on the bottom of the foot.

A great majority of children with flexible flatfeet do not have foot pain. Most likely, they will grow up to be adults without foot pain. That is why all these feet do not necessarily need any treatment. An asymptomatic flatfoot is a variation of normal foot alignment.

Occasionally a child with flexible flatfeet does complain of foot pain. The most common reason for this, is the presence of a tight Achilles tendon. If the Achilles tendon is tight, the ankle will not have full range of motion, and forces which are usually dissipated thru ankle motion are spread to the middle of the foot, which causes pain at the instep.

Whether or not a flexible flatfoot requires any treatment is open for debate. If the child’s foot hurts and there is a tight Achilles present, then treatment is mostly stretching that tendon. Orthotics are not that important to use in this case. The idea is to make a symptomatic flatfoot asymptomatic with Achilles stretching. For the rare case when the foot is painful and the Achilles is not tight, orthotics have a bigger role in stabilizing the position of the foot.

As was stated earlier, the flatfoot is not the most stable base of support when standing. Still a great majority of infants begin to walk any way. Occasionally, a child will have some difficulty overcoming this instability. In these cases orthotics are helpful to stabilize the foot, by rotating the calcaneus inward. This helps the children develop better balance and walk sooner than if they received no treatment at all. With time, a child’s skills will increase, and the need for any type of orthotic will decrease.

Even if they are worn all the time, orthotics do not correct flatfeet. They only support the foot and do not cause foot ligaments to tighten. Over time, the foot ligaments will usually tighten by themselves. We tell our parents to use the orthotics when they are planning to have their children wear shoes. It is OK to barefoot or wear sandals during the summer.