Diagnosis of Flexible Flatfoot in Children: A Systematic Clinical Approach

Flexible flatfoot is one of the most common musculoskeletal disorders and most debated orthopedic diseases. Harris et al¹ divided pediatric flat-foot into symptomatic and asymptomatic, physiological or nonphysiological. While asymptomatic flexible flatfoot is characterized by a natural improvement over time, symptomatic flexible flatfoot alters function and may lead to subjective complaints and objective signs of dysfunction.

Nevertheless, controversy exists about the clinical characterization of flexible flat-foot, the degree of disability it causes in adulthood, and the requirement and choice of treatment.^2,3 According to some reports, flexible flatfoot is not a relevant issue as it is asymptomatic and rarely causes disability.^4-7 Conversely, others reports that flexible flatfoot may cause gait disorders in adulthood.^8-16 Other conditions such as hallux valgus/rigidus, metatarsalgia, subtalar osteoarthritis, tunnel tarsal syndrome, Morton's neuroma, and posterior tibialis tendon dysfunction are often reported as consequences of a flexible flatfoot deformity. Most forefoot deformities are considered a consequence of abnormal subtalar pronation during propulsion.¹⁷

Unfortunately, few longitudinal studies exist on the consequences of flexible flatfoot in adulthood. Furthermore, a consensus on clinical criteria to realize a diagnosis has not been reached. Barry and Scranton¹⁸ reported that the diagnosis of flexible flatfoot is an exclusion diagnosis, based on the static morphology and radiographs of the foot. Bordelon¹⁹ reported that diagnosis of hypermobile flatfoot should include ≥1 of the following signs: forefoot abduction, forefoot supination, and heel valgus.

Methods have been suggested to classify the severity of the collapse in the medial arch or to score the broadening of the foot sole.²⁰ Foot morphology and features of the footprint depend on various factors,^16-21 and several studies have shown that foot function is not necessarily related to foot morphology.^13,22-26

Therefore, flexible flatfoot diagnosis cannot merely rely on a morphologic assessment but should be defined functionally as a foot that, on weight bearing, stays in a state of prevalent or persistent pronation,¹⁷ and for which abnormal foot biomechanics could result in fatigue and overuse syndromes over time.¹⁸ Thus, the evaluation of flatfoot should include a combination of measures and tests besides morphology that assess the foot's dynamic status.²⁵

This article proposes a systematic approach to the diagnosis of flexible flatfoot based on subjective and objective assessments,...