Flat Feet

A low arch, or none visible at all. Feet that roll inwards when you stand. Shoes that wear down along the inner edge. Aching through the arch or the inner ankle after a long day.

A flat foot is not automatically a condition. Arch height varies enormously between people who are entirely comfortable, and a foot is judged on what it does rather than on its profile in a photograph. The question is never “is the arch low”, it is “is the arch low and is something being strained as a result”.

Flexible and rigid, and why the difference matters

A flexible flat foot flattens when you stand and an arch appears when you sit, go up on your toes, or when the big toe is lifted. This is by far the most common presentation, and where it causes no symptoms it needs no treatment.

A rigid flat foot stays flat in every position. That is a different proposition, because it usually means the structure itself is restricted — in younger people often a tarsal coalition, where two bones of the rearfoot are joined by bone or cartilage that should not be there. Rigid, painful, or one-sided flat feet warrant a proper look and often imaging.

When a low arch does start causing trouble

The arch is not doing the work on its own. When it flattens excessively, load is transferred to structures that then complain:

• Plantar fasciitis, the most common consequence, because the fascia is stretched further with every step
• Pain along the inner ankle and up the inside of the shin, including shin splints
• Achilles tendon pain
• Bunions, as the forefoot is loaded across the first joint rather than through it
• Knee, hip and lower back pain, where the rotation the flattening produces travels up the leg
• Fatigue rather than pain — legs that are simply tired at the end of a day on your feet

The one that is time-sensitive

⚠ An arch that has collapsed recently in an adult is not the same thing as an arch that has always been low.

Posterior tibial tendon dysfunction is the tendon on the inside of the ankle gradually failing under load, and it presents as a progressive flattening, usually one-sided, with pain and swelling behind the inner ankle bone, and increasing difficulty rising onto that toe.

It is staged, and the stages matter: caught while the foot is still flexible it is managed with orthoses, bracing and a loading programme. Left to progress, the foot becomes fixed and the conversation changes to a surgical one. Sudden or progressive adult flat foot deserves an appointment rather than a wait.

What the assessment involves

Your podiatrist looks at the foot loaded and unloaded, tests whether the arch restores when you rise onto your toes, checks calf length — a tight calf drives a foot to flatten — assesses the strength of the tendons supporting the arch, and watches you walk.

Just as importantly, the assessment establishes whether the flat foot is actually the reason you are here. Plenty of people with low arches have foot pain caused by something else entirely, and treating the arch would be treating the wrong thing.

Treatment, where treatment is warranted

Footwear first, because a shoe with a firm heel counter and torsional stability does much of the work and costs nothing extra if you were buying shoes anyway.

Then strengthening, particularly of the calf and the tibialis posterior, which is the part most often left out and the part that changes what the foot can tolerate.

Orthotics where load needs redistributing — not to build an arch, but to reduce the strain on whatever is complaining. And where a specific tissue is the problem, that tissue gets its own treatment on top.