Can you explain pes planus (flat foot) in simple terms, including its causes, symptoms, diagnosis, and treatment?

Understanding Pes Planus (Flat Foot) - A Simple Explanation

Pes planus, or flat foot, is a condition where the arch of your foot is flattened or absent, causing the entire sole to touch the ground when standing. 1

What Is Pes Planus?

Pes planus means your foot lacks the normal curved arch along the inside edge. When you stand, your foot appears flat against the ground instead of having that characteristic curve. 1 This can occur in children as a normal developmental variation or develop in adults due to injury or wear-and-tear. 1, 2

Types of Flat Foot

Flexible Pes Planus

• The arch appears normal when you're sitting or standing on your toes, but flattens when you put weight on it. 1
• This is the most common type and usually less concerning. 1
• Most children with flexible flat feet improve naturally as their foot muscles strengthen with age. 1

Rigid Pes Planus

• The arch remains flat whether you're standing or sitting—it never appears. 1
• This type requires specialist evaluation and treatment. 1
• You should be referred to a foot specialist (podiatrist or orthopedic surgeon) if you have rigid flat feet. 3

What Causes Pes Planus?

In Children

• Most childhood flat feet are simply normal variations that resolve with age. 1
• Some genetic conditions can cause flat feet, including 22q11.2 deletion syndrome, Cardio-facio-cutaneous syndrome, and Marfan syndrome. 4

In Adults

• The most common cause is posterior tibial tendon dysfunction—the tendon that supports your arch becomes damaged or weakened. 1, 2
• Repetitive high-impact activities like running, marching, or rucking can damage this tendon over time. 5
• Other foot deformities, limited joint mobility, or conditions like Charcot foot can contribute. 3, 4

Symptoms and Problems

Common Symptoms

• Pain along the inside of your foot or ankle. 6
• Foot fatigue or discomfort with prolonged standing or walking. 6
• Some people have no symptoms at all. 1

Potential Complications

• If you have diabetes or nerve damage (neuropathy), flat feet increase your risk of developing foot ulcers due to abnormal pressure distribution. 3
• The flattened arch changes how forces distribute across your foot, creating pressure points. 5
• Progressive deformity can occur if the posterior tibial tendon continues to weaken, creating a vicious cycle. 5

How Is It Diagnosed?

Your doctor will:

• Watch you stand and walk to see if your arch flattens with weight-bearing. 1
• Ask you to stand on your toes—if the arch appears, it's flexible; if not, it's rigid. 1
• Take X-rays to evaluate bone alignment and stage the severity in adults. 1, 2
• Check for associated conditions like diabetes, peripheral artery disease, or genetic syndromes. 3, 4

Treatment Approach

For Children with Flexible Flat Feet

• If there are no symptoms, simply monitor and encourage maintaining a healthy weight—no treatment is needed. 1
• Symptomatic children should be treated conservatively with shoe modifications or orthotics. 1
• Surgery is rarely needed and has limited evidence supporting it. 1

For Adults with Acquired Flat Feet

The treatment depends on severity and symptoms, but always starts with conservative measures: 1, 2

Activity Modification

• Temporarily reduce high-impact weight-bearing activities to allow tissue healing. 5
• This is mandatory for posterior tibial tendon dysfunction. 5

Footwear and Orthotics

• Internal shoe modifications (medial arch supports placed inside the shoe) provide the most clinical improvement. 6
• External modifications like Thomas heels are also effective but slightly less so. 6
• Custom-made insoles conform to your foot shape and redistribute pressure. 3
• Extra-depth or therapeutic footwear accommodates deformities and reduces pressure on at-risk areas. 3
• Open-backed shoes can reduce pressure on affected structures. 5

Exercise Programs

• Foot-specific exercises targeting stretching, strengthening, and balance can help. 3, 6
• These should be supervised by a physical therapist. 3
• Exercise alone is less effective than shoe modifications but still provides benefit. 6

Surgery

• Reserved for rigid deformities or cases that don't respond to conservative treatment. 1, 2
• Various surgical techniques exist depending on the severity and stage. 2

Special Considerations for High-Risk Patients

If you have diabetes, peripheral artery disease, or neuropathy with flat feet, you need enhanced surveillance: 3

• Have your bare feet inspected at every office visit. 3
• Get a comprehensive foot evaluation at least annually. 3
• Consider referral to a podiatrist or foot care specialist. 3
• Use therapeutic footwear to prevent ulcers. 3
• Practice daily foot self-care including inspection, washing, careful drying, and avoiding walking barefoot. 3

Key Takeaways

• Flat feet in children usually improve naturally and need no treatment unless symptomatic. 1
• Adults with acquired flat feet should start with arch supports and activity modification. 5, 6
• Internal shoe modifications (arch supports) work better than external modifications or exercise alone. 6
• If you have diabetes or nerve damage, flat feet significantly increase your ulcer risk and require specialist care. 3
• Rigid flat feet always require specialist evaluation. 1