The key difference between normal and flat feet lies in the presence (or absence) of a medial longitudinal arch, which affects the footprint and biomechanics of the foot. In normal feet, this arch is present, while in flat feet (also known as pes planus), this arch is either collapsed or entirely absent.
Understanding the Differences
Here's a breakdown of the key distinctions:
1. Arch Structure
- Normal Feet: Possess a visible arch on the inside of the foot when standing. This arch acts as a shock absorber and helps distribute weight evenly across the foot.
- Flat Feet: Have a collapsed or absent arch. When standing, the entire sole of the foot comes into contact with the ground.
2. Footprint
- Normal Feet: Leave a footprint showing a distinct gap between the heel and the ball of the foot, indicating the presence of the arch.
- Flat Feet: Leave a footprint showing the entire sole of the foot, with no visible gap, confirming the absence of the arch. This footprint is a broad, continuous impression.
3. Biomechanics
- Normal Feet: The arch contributes to efficient weight distribution and propulsion during walking and running. It allows for proper pronation (inward rolling of the foot) and supination (outward rolling of the foot).
- Flat Feet: Altered biomechanics can lead to overpronation, where the foot rolls inward excessively. This can cause stress on other joints, potentially leading to pain in the feet, ankles, knees, hips, and lower back.
4. Symptoms
- Normal Feet: Typically asymptomatic, meaning they don't cause pain or discomfort.
- Flat Feet: May be asymptomatic, especially in children. However, they can also cause symptoms such as:
- Foot pain, particularly in the arch or heel.
- Ankle pain.
- Leg cramps.
- Stiffness in the foot.
- Pain that worsens with activity.
5. Diagnosis
- Normal Feet: Diagnosis is typically made through visual examination, observing the presence of the arch when standing.
- Flat Feet: Diagnosis involves visual examination and observing the footprint. A "wet foot test" is commonly used: a wet foot is placed on a dry surface to reveal the footprint. Medical imaging (X-rays) may be used to assess the bone structure in more severe cases.
Summary Table
| Feature | Normal Feet | Flat Feet (Pes Planus) |
|---|---|---|
| Arch | Present | Collapsed or absent |
| Footprint | Gap between heel and ball of foot | Full sole impression |
| Biomechanics | Efficient weight distribution, proper pronation | Overpronation, altered weight distribution |
| Symptoms | Asymptomatic | Foot pain, ankle pain, leg cramps, stiffness, pain with activity |
| Typical Footprint | Arch present | Complete foot outline, no arch present |
In essence, the arch is what defines normal foot structure and function, and its absence or collapse characterizes flat feet.
