The Relationship Between Foot Posture, Validated Foot and Ankle Tests, and Hypermobility in Paediatric Population: A Cross-Sectional Study.

Background: Previous studies have investigated flattened foot arches associated with joint hypermobility using the Beighton scale. The absence of lower limb items below the knee in the Beighton scale questions the relevance of this relationship. Addressing this query, a new validated test has been used to assess joint hypermobility, the Foot and Ankle Flexibility Index (FAFI). Utilising the FAFI, the intention was then to relate it against known reliable morphofunctional foot and ankle tests, and also a validated paediatric physical activity test.

Methods: A total of 205 healthy children, aged 5 to 10 years, participated in this cross-sectional study, which included the Lunge Test, Rest Calcaneal Stance Position (RCSP), Foot Posture Index (FPI) and 6 Minute Walking Test (6MWT).

Results: Significant correlations were found between FAFI and the test variables: RCSP (r = 0.334), Age (r = -0.254), FPI (r = 0.252), and 6MWT (r = -0.240). The multivariable linear regression of the hypermobility component according to FAFI presented an R² value of 24.9%.

Conclusions: This study suggests that younger children and those with greater foot and ankle hypermobility have a more pronated foot stance, a greater range of ankle dorsiflexion, and a decreased walking speed/distance. Given the public health implications of unnecessary attention to many paediatric flatfeet presentations, these findings increase clinical clarity, using the new and validated FAFI.