Critical Review: The F-Words Relating to Symptomatic Flexible Paediatric Flat Feet (Urukalo et al., 2025) | Find Your Stride | Edinburgh Podiatrist

Background

Flexible flat feet (where the arch collapses during weight-bearing but reforms when unloaded) are common in children and often seen in clinics concerned with running or walking discomfort. Urukalo and colleagues’ 2025 paper takes a fresh approach, using the “F-words” framework (fitness, functioning, friends, family, fun, and future) to map 42 symptoms linked with symptomatic flexible flat feet in children.

This study is not about treatment outcomes or gait metrics per se, but about clarifying what symptoms clinicians and parents should recognise as clinically meaningful. That’s important for podiatrists working with young athletes or active kids whose “flat feet” may or may not contribute to running and walking issues.

Flexible flat feet - where the arch collapses during weight-bearing but reforms when unloaded are common amongst children

Summary of the Study

The authors conducted a scoping review across over 1,300 citations, finally including 133 studies from 29 countries. They analysed reported symptoms and categorised them using the “F-words” model, derived from the WHO’s International Classification of Functioning (ICF-11). Key findings:

• Pain was the most common symptom, reported in 124 studies, especially in the hindfoot, midfoot, and knee.

• Reduced lower limb function (e.g., altered gait, reduced balance, tripping) was present in 102 citations.

• Fatigue and endurance loss were frequent, with children tiring faster during walking, running, or standing.

• Reduced participation in physical activities and sports appeared in 30 studies, linking flatfoot symptoms with social and confidence impacts.

• No symptoms related to “fun,” suggesting a gap in how children’s enjoyment and motivation are measured.

Critical Appraisal

Strengths

• Comprehensive scope: The inclusion of over 130 studies gives a panoramic view of the evidence; academic, clinical, and grey literature alike.

• Innovative framework: Applying the “F-words” model offers a child-centred way to interpret symptoms beyond biomechanics alone.

• Clinical relevance: For podiatrists, the review clarifies that “symptomatic” flat feet are about function and participation, not just arch height.

Limitations

• Symptom overlap and subjectivity: Many symptoms (pain, fatigue, poor balance) are non-specific and may relate to overall lower limb development, not flatfoot posture alone.

• No distinction between cause and correlation: It remains unclear whether flatfoot causes these symptoms or merely coexists with them.

• Lack of gait-specific evidence: Despite mentioning altered walking and running, few studies used objective gait analysis—limiting insight for performance-focused clinicians.

• No “fun” factor: The absence of the “fun” category suggests researchers may be overlooking psychosocial and motivational aspects of physical activity - critical for adherence to interventions like strengthening or orthotic use.

Clinical and Performance Implications

For podiatrists, coaches, and parents focused on running and walking:

• Pain ≠ automatic pathology. A flat foot without pain or activity limitation is often normal, particularly in children under 5.

• Fatigue and reduced balance may indicate when orthotics, strengthening, or gait retraining could help.

• Performance link: Reduced endurance and tripping may explain slower sprint times or coordination issues in junior athletes, even when no overt pain is present.

• Monitor function, not just structure. The F-words reminds us to look at fitness and function - how the foot performs dynamically rather than fixating on its shape.

Where the Research Falls Short

Despite its breadth, this review reveals a persistent evidence vacuum:

• No longitudinal data on whether symptomatic flat feet in childhood predict adult foot pain or running inefficiency.

• Sparse use of motion analysis or kinetic data to link symptoms to performance metrics.

• Minimal discussion of footwear or surface interaction factors highly relevant to podiatry and running performance.

Until these gaps are addressed, clinicians must continue blending evidence with practical gait assessment and individualised care.

Takeaway for Podiatrists and Runners

Urukalo et al. provide valuable consolidation of what’s reported about symptomatic flexible flat feet but not yet what’s proven. The “F-words” lens helps us think holistically about young patients: not just the arch, but the athlete.

For practitioners, the key message is to treat symptoms, not shapes and to use functional and endurance testing when assessing young runners or walkers with flat feet.

In Summary

This scoping review reframes paediatric flatfoot from a static structural issue to a multidimensional functional one. But until we have longitudinal, gait-based evidence, the implications of flexible flat feet for running and walking performance remain suggestive rather than conclusive.

Citation

Urukalo, J., Banwell, H., Williams, C., Morrison, S. C., & Kumar, S. (2025). The F-words relating to symptomatic flexible flat feet: A scoping review. PLOS ONE, 20(5), e0320310. https://doi.org/10.1371/journal.pone.0320310

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