A flat-looking foot is not automatically a problem. Many people have low arches and remain comfortable, active and unrestricted throughout life. Painful flatfoot is different: the foot’s shape, alignment or supporting tendons may no longer be coping with everyday load. Knowing how to assess painful flatfoot helps identify when simple measures may be reasonable and when a detailed specialist opinion is warranted.
Start with the pattern of pain
The location and behaviour of pain offer useful clues. Pain along the inside of the ankle or arch may involve the posterior tibial tendon, a major tendon that supports the arch. Pain beneath the heel can coexist with a flat foot but may arise from a separate source, such as plantar fascia irritation. Pain on the outside of the ankle or foot can occur when a collapsing foot places pressure on structures that are not designed to carry so much load.
Consider when the pain occurs. Is it present with the first steps in the morning, after standing at work, during sport, or after a long walk? Does it settle with rest, or is it progressing despite reduced activity? A foot that becomes increasingly painful, fatigued or swollen through the day deserves closer assessment, particularly when symptoms affect work, exercise or footwear choices.
Also note whether one foot is substantially more painful or flatter than the other. Flat feet are often present on both sides, but a newly changing arch on one side is more concerning than a lifelong, symmetrical low arch.
Look at the foot while standing
A useful home observation begins barefoot on a firm, level floor. Look at the feet from the front and behind, without trying to correct their position. In a painful flatfoot, the heel may roll outward and the arch may lower towards the floor. From behind, more toes may be visible on the outer side of the affected foot. Clinicians sometimes call this the “too many toes” sign.
Compare both sides for changes in arch height, heel alignment and ankle swelling. Pay attention to whether the foot appears to spread or lengthen. Some people notice that shoes which once fitted comfortably become tight across the forefoot, or that one shoe wears down more quickly on its inner or outer edge.
These observations are only indicators, not a diagnosis. A low arch can be flexible and symptom-free, while a foot that appears only mildly flat can still be painful because of tendon damage, arthritis, ligament injury or joint impingement.
Check whether the arch reforms
Next, sit down or stand on tiptoes while holding a stable bench or wall for balance. In a flexible flatfoot, the arch may become more visible when weight is removed or when the heel rises. In a more rigid foot, the arch may remain low and the hindfoot may be difficult to correct.
This distinction matters because a flexible deformity and a stiff, arthritic or longstanding deformity may require different treatment approaches. Do not force the foot into position if this causes pain.
Try a supported single heel raise
If it is safe to do so, hold a bench and attempt to rise onto the ball of one foot at a time. A healthy posterior tibial tendon helps lift the heel and turn it slightly inward during this movement. Difficulty completing a single-leg heel raise, pain along the inner ankle, or an inability to bring the heel inward may indicate that the tendon and arch-supporting structures need assessment.
This is not a test to push through. Stop if there is sharp pain, loss of balance or significant weakness. Children, older adults and anyone with poor balance should avoid attempting it without support or clinical guidance.
Assess movement, strength and function
Painful flatfoot is assessed by function as much as appearance. Think about what the foot can no longer do comfortably. You may be avoiding stairs, cutting walks short, giving up running, or feeling unsteady on uneven ground. Some patients describe a gradual loss of walking tolerance; others develop a distinct limp after activity.
Check whether ankle movement is restricted, especially when the knee is straight and then bent. Tight calf muscles can increase strain through the arch and contribute to flattening over time. However, restricted movement can also reflect arthritis or a bony limitation, so it should not be assumed to be simple tightness.
Swelling, tenderness or warmth around the inner ankle should be taken seriously. So should pain at the sinus tarsi, the hollow area in front of the outer ankle bone, where a flatfoot can produce joint impingement. If there has been a recent injury, a sudden change in shape, bruising or inability to bear weight, prompt medical review is appropriate.
Consider the person, not just the arch
A thorough assessment considers age, activity, health history and the speed of change. In children, a flexible flatfoot is common and often causes no symptoms. Assessment is more important when a child has pain, stiffness, recurrent ankle sprains, difficulty keeping up with peers, or a foot that appears markedly different from the other side.
In adults, painful flatfoot may develop gradually as the posterior tibial tendon weakens, ligaments stretch and joints become less well aligned. Previous injury, inflammatory arthritis, diabetes, nerve conditions, obesity and calf tightness can all influence symptoms and treatment planning. Some people have longstanding flat feet that only become problematic after a change in work demands, weight, fitness or footwear.
Footwear is relevant but rarely tells the whole story. Supportive shoes and orthoses can reduce symptoms in some flexible flat feet by improving comfort and controlling load. They cannot repair a torn tendon, reverse established arthritis or reliably correct a progressing deformity. If footwear changes provide only short-lived relief, it is sensible to investigate why the foot remains painful.
When imaging and specialist examination are needed
A clinician will examine the foot while sitting, standing and walking. This includes checking joint motion, tendon strength, areas of tenderness, heel alignment, calf tightness, circulation and sensation. Gait assessment can reveal compensations that are difficult to notice yourself.
Weight-bearing X-rays are commonly used because they show the relationship of the bones and joints under load. Depending on the findings, ultrasound may assess tendon changes, while MRI or CT can provide more detail about tendons, ligaments, cartilage, arthritis or complex deformity. Imaging is interpreted alongside the clinical examination, not in isolation. An X-ray may show a low arch in someone without pain, while subtle tendon pathology can be highly symptomatic.
For patients considering surgery, assessment also establishes whether non-surgical treatment has been adequate and what is realistically causing the pain. Reconstructive surgery is not one operation for every flatfoot. It may involve tendon work, ligament reconstruction, bone realignment, joint fusion or a combination of procedures, depending on flexibility, arthritis, tendon health and deformity severity.
Warning signs that should not wait
Seek timely medical assessment for a painful flatfoot that is worsening, changes shape rapidly, causes persistent swelling, or limits normal walking. Earlier review is particularly sensible after an injury, if you cannot perform usual activities, or if pain continues despite sensible footwear, activity modification and prescribed treatment.
Urgent assessment is needed for severe pain after trauma, inability to bear weight, a hot red swollen foot, fever, a wound, new numbness, or colour changes in the toes. People with diabetes, reduced sensation or circulation problems should not wait for a minor-looking foot issue to become severe.
A clear next step for painful flatfoot
The purpose of assessment is not simply to label a foot as flat. It is to determine what structures are painful, whether the deformity is flexible or fixed, and whether it is stable or progressing. That information supports a treatment plan matched to the individual, from targeted non-surgical care through to reconstructive options where appropriate.
If your arch has changed, your walking is becoming limited, or pain is stopping you from living as actively as you would like, a specialist foot and ankle assessment can provide clarity. Sydney Foot & Ankle Surgeon can help patients understand the cause of their symptoms and make informed decisions about the most suitable path forward.