Hypermobile Flatfoot And Pediatric Obesity: What You Should Know
A similar study out of Spain found similar results when researchers compared the arch height of obese and non-obese children.3 The authors concluded that obese children had lower medial longitudinal arch heights. They did not, however, relate whether lower arch heights were due to a more pronounced fat pad or whether they were due to a more structurally related etiology.
Another study based in Australia also found that obese children had flatter feet.4 Researchers then postulated that this flatter foot morphology could be caused by structural changes in the anatomy of these children’s feet and the morphology can affect function as these children mature into adulthood.
Interestingly, another group of Australian researchers studied the effects of medial midfoot fat pad thickness and how it correlates to plantar pressures in school age children.5 Although the authors did find some correlation between the two factors, they also admitted that this correlation was rather low and more intense study was needed to solidify a more meaningful conclusion.
The last but potentially most telling of the research published in Australia on this topic is a study that took this concept into a more biomechanical realm than the others and examined the kinematics of gait.6 The study patients underwent analyses that measured certain aspects of their gait while they were being filmed walking. What the authors found was that obese children had more “gait asymmetry … a greater stride width … pointing to a slower, more tentative normal speed.” They also found that the obese children were more unstable at a slower walking speed and that they had trouble walking at a faster pace. Additionally, they found that obese children had a more flat-footed and abducted gait at all phases of the gait cycle.
In a study of 835 preschool age children in Austria, the authors found that the most common study group that displayed a flat-footed morphology was the obese male children.7 Researchers went so far to say they observed “a highly significant prevalence of flatfoot” in the overweight child. A study based in Italy found similar results.8 In a study of 243 children between the ages of 8 to 10 years of age, the authors found those who were obese had a higher incidence of moderate and very marked flat-footedness in comparison to their non-obese classmates.
A group in Germany chose a slightly different route to identify the feet of their patients.9 They chose to classify the feet by how they looked and found that overweight children were much more likely to have flat feet or what they called “robust” feet. They did not quantify exactly what “robust” referred to but the description of flat feet was more descriptive of the morphology of the overweight children in any case.
The Taiwanese were so interested in this phenomenon that they generated three separate studies concerning the prevalence of flexible flatfoot in obese school age children. Within these three research articles, researchers evaluated a total of over 4,700 children. This comprises the largest cumulative sample size ever seen with this topic.
The first study was comprised of 1,598 children and its conclusion was that obesity was one of the risk factors of developing this foot type.10 A study concluded one year earlier with a sample size of over 2,000 children showed that male children who were obese were 2.66 times more likely to have a flatfoot morphology than their non-obese classmates.11 The study also noted that female children who were obese were 1.39 times more likely to have this foot morphology than females who were not obese. In addition, researchers noted that obese children of either sex showed this foot morphology between the ages of 7 and 8.