What it is

Flat feet, or pes planus, describe a foot where the arch is lower than usual during standing and walking. A foot that “collapses” or “over pronates” can place stress on several parts of the body and lead to injuries in these areas.

In most cases, arch height is determined genetically, and some people are born with a natural tendency to have flatter feet than others. In some cases, however, the foot collapses later in adulthood. This is normally due to the deterioration of muscles or tendons in our lower leg through overuse and dysfunction, and is often referred to as adult-acquired flat foot. This is a condition that requires prompt attention.

In children, a flexible flat foot is often a normal variant that improves with age.

The key point is that an arch shape is not a diagnosis by itself. Symptoms arise when load and capacity are mismatched across the plantar fascia, posterior tibial tendon, and midfoot joints.

What happens when it occurs

Greater rearfoot eversion and midfoot motion increase demand on the posterior tibial tendon and plantar fascia, and can lead to injury of these structures during overuse. If strength and control lag, tissues become sensitive and daily tasks feel heavy.

Changing footwear, step mechanics, and strength can restore balance, allowing the foot to share the load again.

Common causes and risk factors

  • Family foot shape and ligament laxity
  • Rapid increases in walking or running volume, hills, or long shifts on hard surfaces
  • Calf tightness and reduced posterior tibial strength
  • Higher body weight and prolonged standing work

Who is most affected

School‑age children with flexible feet, active adults in standing jobs, and runners building distance or hills. Previous injury may impact loading and result in injury.

Typical symptoms

  • Aching along the inner arch or behind the inside ankle bone
  • Morning or start‑up stiffness under the arch
  • Fatigue with long walks, hills, or uneven ground

When to seek care

If pain limits walking or running, if the arch collapses suddenly after an injury, or if you cannot perform a single‑leg heel raise.

How we diagnose

History and examination, including single‑leg heel raise, arch height index, posterior tibial strength tests, and gait analysis.

Ultrasound or MRI is used when a tear is suspected or if progress stalls despite a structured plan.

Management

  • Taping can be used to support the foot and change its position. It can be used standalone or in combination with orthotic therapy.
  • Footwear review and trial of supportive trainers or stability footwear
  • Progressive strengthening for the posterior tibial tendon, calves, and foot intrinsics
  • Gait coaching: slightly shorter steps, quiet landings, and cadence tweaks for runners
  • Orthoses can be used to help support the foot and reduce the workload on certain muscles, ligaments, and tendons. They also offer a long-term solution that requires minimal effort on the patient’s behalf.
  • Laser Therapy can be used if your flat feet are causing you to experience pain. This can be done as part of a comprehensive treatment plan aimed at eliminating your symptoms, rebuilding strength, and returning you to the things you want to be doing.
  • Shockwave therapy can be used to stimulate the healing response.
  • Dry Needling to create a “twitch” response that allows the muscle to elongate and return to its normal length. This lengthening results in reduced muscle tightness and tension.

Rehabilitation milestones

Phase 1 weeks 0–2: pain control, isometrics (calf and posterior tibial), gentle foot intrinsic work, flat walks.

Phase 2 weeks 2–6: heavy slow calf raises, tibialis posterior raises, short‑foot drills, balance.

Phase 3 weeks 6–12: hills and uneven ground exposure, hopping progressions, graded return‑to‑run.

Phase 4 weeks 12–16: performance drills and sport integration; orthoses re‑trial decisions.

Readiness to progress

  • Single‑leg heel raise 20–25 reps with reasonable arch control
  • Y‑Balance within 90 per cent of the other side
  • Run‑walk or hill session completed without next‑day flare

Prevention

  • Maintain calf length and strength
  • Rotate footwear suited to the terrain and workload
  • Progress weekly distance and hills gradually

Australia snapshot

  • A common reason for presentation in primary care and sports clinics
  • Standing occupations and runners form a large share of cases
  • Supportive footwear and orthoses trials are widely accessible

Latest insights

Arch shape is only part of the story. Strength, cadence, and footwear choices all contribute to comfort.

Orthoses are tools, not crutches. Keep what clearly helps and keep training your feet.

Frequently Asked Questions

No. Many people are comfortable without them. Use a time‑limited trial and keep them only if comfort and function improve.

Yes. Build strength, adjust cadence, and progress distance and hills in small steps.

Yes. Foot intrinsics, posterior tibialis, and calf work improve support and endurance.

If a tendon tear is suspected or if progress stalls after a thorough programme.

Supportive trainers with stable midsoles and adequate cushioning. Fit and comfort trump labels.

Alternate tasks, use supportive footwear, and plan short movement breaks on hard surfaces.

Most flexible feet are painless and improve with growth. Treat symptoms, not appearance.

This is very rarely required to treat and manage flat feet, but in extreme cases, surgery can be necessary. Most flexible feet will improve with growth. We treat symptoms, not appearance.