Flexible Flatfoot—Epidemiology, Pathophysiology and Clinical Aspects: A Review Focused on Less-Invasive Surgical Treatment in Children

Background/Objectives: To give the proper context to children’s flexible flatfoot (FF), considered to be a crippling deformity by some authors and a variation of normal foot development by others, it requires treatment only in a few symptomatic cases. During the last 20 years, according to the literature, less-invasive surgery (LIS) has been extensively performed on FF to restore the longitudinal arch of the foot, to improve FF’s function, and to prevent its presumed unfavorable evolution into adulthood. Methods: The literature was searched using the following keywords and phrases: FF, FF epidemiology, FF etiopathogenesis, FF physiopathology, FF diagnosis, FF treatment, and FF subtalar arthroereisis. The primary sources were PubMed and The Cochrane Library. Results: Epidemiological studies carried out on many people, some of them performed in a military environment, reported FF prevalence in adults of about 15%, but most flexible flatfeet (FFT) were found to be asymptomatic. In the pediatric population, FF prevalence is higher, reaching almost 40–45% up to 6 years of age and decreasing thereafter with increasing age, owing to the spontaneous formation of the longitudinal arch of the foot. Like adults, children and adolescents with FF are rarely symptomatic. These data seem to be in contrast with the high number of symptomatic children and adolescents with FF who are treated by LIS. However, epidemiological studies reflect general populations while less invasive surgical series represent selected referral cohorts. Conclusions: According to the literature, several studies on LIS report high numbers of FF operated on every month. These data raise concerns; therefore, we believe that indication for LIS must be carefully evaluated in the future to avoid overtreatment of FF.