Hypermobile Flatfoot And Pediatric Obesity: What You Should Know

Given the increasing prevalence of childhood obesity, this author examines the emerging connection with pediatric flatfoot via a thorough review of the current research and discusses the need for further research to support treatment of flatfoot in this population.

Almost daily, you can turn on your TV or open your favorite newspaper and learn about the “national health crisis” that is obesity. There is also a tremendous amount of literature concerning the long-term health pitfalls of morbid obesity and how it can affect the heart, liver, kidney and lymphatic system. Obviously, obesity can also lead to diabetes and a whole host of other health-related issues.

   We are also starting to realize that these poor habits begin in our youth and translate to our overall health as adults. This is very apparent if you’ve ever watched The Jamie Oliver Experiment. In this show, the titular young chef travels the United States and tries to revamp cafeterias in public schools to have a menu that is generally healthier, and convince our nation’s youth to modify their lifestyles and help them attain health into adulthood.

   As a parent, I am very concerned about my children’s health but does their health translate to their feet as well? Are obese children more prone to a certain foot type? If that is the case, how does that relate to their general health?

A Closer Look At How Researchers Are Identifying Flatfoot In Study Populations

Before starting the discussion of flatfoot studies and their outcomes, I would like to discuss the methodologies of many of these authors with respect to how they determined a flatfoot condition. Many of the studies that I will discuss employed modern methods of determining foot type. We use many of these methods (such as weightbearing radiographic measurements and evaluation of patients in stance and ambulation) in the day-to-day practice of podiatry.

   Study authors used these and other more sophisticated methods of determining flatfoot. The other methods included: electronic footprint capture during gait; ultrasonography to measure fat pad thickness; dynamic plantar pressure analysis; and three dimensional laser surface measures. It is important to point out the use of these additional measurement techniques as they lend credence to the outcomes and conclusions of the studies. Without these modalities, one might be tempted to pass off many of the conclusions derived from these studies as “user bias.” However, most of these studies also combined sophisticated measurement techniques with hard data and statistical analysis. This was one the reasons I selected these studies for this review.

   Other studies throughout the world’s medical communities have found similar results when studying the relationship with childhood obesity and flatfoot. In doing the research for this article, it became evident that every corner of the world is struggling with this problem of obesity and flatfoot, given the type of research that is occurring with the pediatric population.

What The Research Says About The Effect Of Weight On Pediatric Feet

As we know, infants do not have much of an arch. Even new walkers do not display much of an arch height. Up until approximately the age of 2, when the arch becomes recognizable, it is virtually impossible to assess foot type unless significant pathology is present.

   One study attempted to correlate obesity and low arch height in adults.1 The authors found, using footprint-based estimates, that study patients who were obese displayed lower arch heights than their non-obese adult counterparts. Although this study did not focus on the pediatric population, it served as a springboard for others to investigate this topic in obese children as well.

   Another study in Australia measured the same basic premise of arch height in obese children.2 The authors found that “obese children had fatter and flatter feet compared to normal weight children.” They did caution, however, that more studies needed to be completed to assess “… the functional and clinical relevance of the increase [sic] … .”2

   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.

   The last of the Taiwanese studies published recently evaluated flatfoot in children between the ages of 5 and 13.12 Researchers found that when combining the children they considered “overweight” and “obese,” there was a very large percentage who had flat feet. Fifty-six percent of children they classified as “obese” had flat feet and 31 percent of those who were “overweight” had flat feet. The one observation with this study that one should note is that the “normal” children had a 27 percent prevalence of obesity. This calls the statistical analysis of the authors’ data into question but we cannot overlook their conclusion.

In Search Of EBM For Flatfoot Treatment In Obese Pediatric Patients

Much of the research shows that to some degree or another, obesity in childhood can lead to flatfoot. Now how do we transfer this knowledge to the care of this pediatric population?
Much of the studies talk about the foot type but few refer to the consequences of this foot type. One journal article that talks about obesity as a potential cause of flatfoot also expresses concern that one should treat this carefully and consider patient adherence and parental involvement in following the treatment plan.13

   There are only two papers relating the factors of pediatric obesity, flatfoot and pain. The relationship of the three factors in these articles is not direct but the authors talk of the factors in broader terms as potential explanations for the foot type causing pain. One study discusses pediatric obesity as a potential cause for flatfoot pain via Sever’s disease.14 The other study discusses an increase in symptoms in pediatric patients with rigid flat feet if the patients were in the 95th percentile or higher in weight for their age.15 Once again, there is no literature that offers evidence to suggest a youngster who is obese will eventually become an adult with painful flatfoot.

   This is where the vacuum exists. This is our biggest hurdle to overcome to begin the process of justifying the treatment of the pediatric flatfoot. Whether the flatfoot is caused by obesity, connective tissue disorders, severe equinus, compensated metatarsus adductus or the myriad of other potential causes, our next hurdle is to show that left to its own devices, this foot type will cause lasting pain and potential disability if left untreated or supported.

   The biggest problem we encounter is how to design a study protocol to test this theory. It is unreasonable to expect that a study protocol would suggest having a treatment group and a control group. In such a hypothetical study, one group would wear orthotics or undergo corrective surgery to reconstruct the foot into a more “neutral” and functional foot type. The other group would just have simple observation. This study would follow the “subjects” over the course of a generation and the results would be calculated regardless of the patient’s lifestyle or job choice. The “subjects” would be followed by a group of practitioners or via a multicenter study over the course of the doctors’ careers and would only be subject to statistical scrutiny as the pediatric patients mature into their adult lives, or beginning in their late teens. 

   Until a project such as the one described occurs, the evidence basis to justify treatment of flatfoot in obese pediatric patients remains elusive.

   Dr. Raducanu is the President and a Fellow of the American College of Foot and Ankle Pediatrics. He is also a Fellow of the American College of Foot and Ankle Surgeons. Dr. Raducanu is in private practice in Philadelphia.

References

1. Wearing SC, Hills AP, Byrne NM, Hennig EM, McDonald M. The arch index: a measure of flat or fat feet? Foot Ankle Int. 2004; 25(8):575-581.
2. Riddiford-Harland DL, Steele JR, Baur LA. Are the feet of obese children fat or flat? Revisiting the debate. Int J Obes (Lond); 2010 June 22 E-Pub.
3. Villarroya MA, Esquivel JM, Tomas C, et al. Assessment of the medial longitudinal arch in children and adolescents with obesity: footprints and radiographic study. Eur J Pediatr. 2009; 168(5):559-67.
4. Mickle KJ, Steele JR, Munro BJ. The feet of overweight and obese young children: are they flat or fat? Obesity (Silver Spring). 2006; 14(11):1949-53.
5. Riddiford-Harland DL, Steele JR, Baur LA. Medial midfoot fat pad thickness and plantar pressures: are these related in children? Int J Pediatric Obes. 2011; 6(3-4):261-6.
6. Hills AP, Parker AW. Gait characteristics of obese children. Arch Phys Med Rehabil. 1991; 72(6):403-7.
7. Pfeiffer M, Kotz R, Ledi T, Hauser G. Sluga M. Prevalence of flat foot in pre-school-aged children. Pediatrics. 2006; 118(2):634-9.
8. Bordin D, DeGiorgi G, Mazzocco G, Rigon F. Flat and cavus foot, indexes of obesity and overweight in a population of primary-school children. Minerva Pediatr. 2001; 53(1):7-13.
9. Mauch M, Grau S, Krauss I, Maiwald C, Horstmann T. Foot morphology of normal, underweight and overweight children. Int J Obes (Lond). 2008; 32(7):1068-75.
10. Chen KC, et al. Relevant factors influencing flatfoot in preschool-aged children. Eur J Pediatr 2011;170(7):931-6.
11. Chang JH, Yeh CJ, Tung LC, Yang JF, Yang SF, Wang CH. Prevalence of flexible flatfoot in Taiwanese school-aged children in relation to obesity, gender and age. Eur J Pediatr. 2010; 169(4):447-52.
12. Chen JP, Chung MJ, Wang MJ. Flatfoot prevalence and foot dimensions of 5- to 13-year-old children in Taiwan. Foot Ankle Int. 2009; 30(4):326-32.
13. Napolitano C, Walsh S, Mahoney L, McCrea J. Risk factors that may adversely modify the natural history of the pediatric pronated foot. Clin Podiatr Med Surg. 2000; 17(3):397-417.
14. Hefti F. Foot pain [translated from German]. Orthopade. 1999; 28(2):173-9.
15. Luhmann SJ, Rich MM, Schoenecker PL. Painful idiopathic rigid flatfoot in children and adolescents. Foot Ankle Int. 2000; 21(1):59-66.

   For further reading, see “Point-Counterpoint: Asymptomatic Flatfoot In Kids: Should You Treat It?” in the January 2010 issue of Podiatry Today.