Flat foot

In summary: not every flat foot is a problem; many are flexible and asymptomatic. We treat when there is pain or fatigue, with insoles made from your gait study —not simply “because the arch is low”.

Flat foot is the reduction of the inner arch of the foot when bearing weight. Here there is an important nuance: not every flat foot is a problem. There are flexible ones, often without any symptoms, and there are those that do cause pain or fatigue.

The job is to distinguish between them and treat only when necessary —with insoles and, in specific cases, other options—, not to prescribe an insole “because the arch is low”.

Flat foot in adults: when it is a problem

A flat foot that has never bothered anyone can start to cause issues from the age of 40 or 50. The most common cause is fatigue of the posterior tibial tendon, the one that supports the arch on the inner side. When this tendon overworks for years, it may begin to fail: the foot progressively flattens, pain appears on the inside of the ankle, and it becomes difficult to stand on tiptoes.

This condition should not be left untreated. Detected early, it usually responds well to custom insoles that offload the tendon, combined with prescribed exercise. If left to evolve, the deformity can become rigid and the options become more complicated.

Another sign to watch out for is pain that appears away from the foot. An arch that collapses changes the way you walk, and this can overload the ankle, knee, or hip. Therefore, the assessment looks not only at the foot: it looks at how you walk. Flat foot also favors other frequent discomforts, such as plantar fasciitis.

How we assess a flat foot in the consultation

The first question is not “how flat it is”, but “what it does to you”. We explore the foot while sitting and bearing weight, and check if the arch appears when you stand on tiptoes: this is the typical sign of a flexible flat foot. At the first visit, we have ultrasound available, so if we suspect the posterior tibial is suffering, we can check it right then.

Afterwards, we perform a gait study with a 3D scanner: we see how you distribute your weight and how the foot behaves when you walk. With all this, we decide whether treatment is necessary, what needs to be offloaded, and what the insole should be like —if one is needed at all.

Flat foot and footwear: what really helps

There is no universal “flat foot shoe”, but there are useful criteria. Look for a firm heel counter that does not bend when pressed with your fingers, and a sole that only flexes in the toe area. Completely flat and soft shoes tend to tire a symptomatic flat foot more.

And be careful with the idea of “corrective shoes”: footwear does not correct the shape of the foot. What it does do is provide a good base for the foot to work comfortably and so that the insole, if needed, can do its job.