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Flatfoot and Injuries

Following a literature review performed in 2003 that is being annually updated, The Running Clinic always defended the point that installed anatomical and biomechanical peculiarities (present since a long period of time) such as flat and cavus feet OR pronating and supinating feet do not cause musculoskeletal disorders. Some recently published papers exploring this topic are exposed here.

 

Scientific paper review #1

Foot pronation is not associated with increased injury risk in novice runners wearing a neutral shoe: a 1-year prospective cohort study. (2013- Nielsen)

A high quality study that was just published in June by Rasmus Nielsen and colleagues suggests that the level of pronation or supination do not increase the risk of injury in runners. They recruited 927 novice runners aged 18 to 65, assessed their foot biomechanics, had them to run with a pair of Supernova Glide 3 (neutral traditional running shoes, TRC rating = 50%), and monitored injuries during the following year.

 

Scientific paper review #2

Association Between Foot Type and Lower Extremity Injuries: Systematic Literature Review With Meta-analysis (Tong-2013)

Jasper Tong and Pui Kong reviewed the literature and performed a generally well-done meta-analysis of the risk of injury depending on foot types. However, results do not convince us about the stated conclusion: "High arch and flat-foot foot types are associated with lower extremity injuries".

 

Here are some critics that, again, bring us to keep our position and to defend the statement that there is NO link between arch type and lower limb overuse pathologies.

 

  1. A systematic review is as good as the studies it includes. Cross-sectional and case control studies are put together with prospective studies. Despite a stronger level of evidence, more rigorous methodology and results that are most of the time neutral, prospective studies are diluted among studies of lower quality.
  2. Authors seem to have missed a few interesting studies in their literature review process, in addition to newly published studies... which would decrease the strength of their conclusion to shift towards more "neutral" statements. (Dixon-2006, Duffey-2000 Hreljak-2000, Lun-2004, McCrory-1999, Messier-1991, Messier-1995, Moen-2012, Montgomery-1989, Nielsen-2013, Pohl-2009, Rome-2001, Thijs-2008, Warren-1984, Wen-1997, Willem-2006, Yagi-2012). If some studies were excluded by the authors for any methodological reason, they did not justify such decision.
  3. A lot of variation can be observed in the classification of foot types and the definition of an injury, which produce conclusions based on heterogeneous data that are certainly not considerably strong.
  4. Let's forget about the science and think for a moment. I'm 30 years old, I have flat feet because my father and my grandmother gave me that genetic component. And guess what, I am adapted to these flat feet since they are part of my since years and years. One day, I start to feel pain in my knee. I seek the help of a health professional, who looks at my feet and prescribes orthotics to me... warning me that I will have to wear them for the rest of my life. What? What did you just say, Doctor?

 

Study

Objective : To investigate if running distance to first running-related injury varies between foot postures in novice runners wearing neutral shoes.

Design : A 1-year epidemiological observational prospective cohort study. Setting Denmark. Participants A total of 927 novice runners equivalent to 1854 feet were included. At baseline, foot posture on each foot was evaluated using the foot-posture index and categorised into highly supinated (n=53), supinated (n=369), neutral (n=1292), pronated (n=122) or highly pronated (n=18). Participants then had to start running in a neutral running shoe and to use global positioning system watch to quantify the running distance in every training session.

Main outcome measure : A running-related injury was defined as any musculoskeletal complaint of the lower extremity or back caused by running, which restricted the amount of running for at least 1 week. Results During 1 year of follow-up, the 1854 feet included in the analyses ran a total of 326 803 km until injury or censoring. A total of 252 participants sustained a running-related injury. Of these, 63 were bilateral injuries. Compared with a neutral foot posture, no significant body mass index-adjusted cumulative risk differences (RD) were found after 250 km of running for highly supinated feet (RD=11.0% (−10% to 32.1%), p=0.30), supinated feet (RD=−1.4% (−8.4% to 5.5%), p=0.69), pronated feet (RD=−8.1% (−17.6% to 1.3%), p=0.09) and highly pronated feet (RD=9.8% (−19.3% to 38.8%), p=0.51). In addition, the incidence-rate difference/1000 km of running, revealed that pronators had a significantly lower number of injuries/1000 km of running of −0.37 (−0.03 to −0.70), p=0.03 than neutrals.

Conclusions : The results of the present study contradict the widespread belief that moderate foot pronation is associated with an increased risk of injury among novice runners taking up running in a neutral running shoe. More work is needed to ascertain if highly pronated feet face a higher risk of injury than neutral feet.  

 

Study #2 

Objective : To investigate the association between non-neutral foot types (high arch and flat foot) and lower extremity and low back injuries, and to identify the most appropriate methods to use for foot classification.

Methods : A search of 5 electronic databases (PubMed, EMBASE, CINAHL, SPORTDiscus, and ProQuest Dissertation and Thesis), Google Scholar, and reference lists of included studies was conducted to identify relevant articles. The review included comparative cross-sectional, case control, and prospective studies that reported qualitative/quantitative associations between foot types and lower extremity and back injuries. Quality of the selected studies was evaluated and data synthesis for the level of association between foot types and injuries was conducted. A random-effects model was used to pool odds ratios (OR) and standardized mean differences (SMD) results for meta-analysis.

Results : Twenty-nine studies were selected and included for meta-analysis. A significant association between non-neutral foot types and lower extremity injuries was determined [OR (95% confidence intervals (CI) = 1.23 (1.11, 1.37); p < .001]. Foot posture index (FPI) [OR = 2.58 (1.33, 5.02); p < .01] and visual/physical examination [OR = 1.17 (1.06, 1.28); p < .01] were 2 assessment methods using distinct foot type categories that displayed significant association with lower extremity injuries. For foot assessment methods using a continuous scale, measurements of Lateral Calcaneal Pitch Angle [SMD = 1.92 (1.44, 2.39); p < .00001], Lateral Talo-Calcaneal Angle [SMD = 1.36 (0.93, 1.80); p < .00001], and Navicular Height (NH) [SMD = 0.34 (0.16, 0.52); p < .001] displayed significant effect sizes in identifying high arch foot, while Navicular Drop Test [SMD = 0.45 (0.03, 0.87); p < .05] and Relaxed Calcaneal Stance Position [SMD = 0.49 (0.01, 0.97); p < .05] for flat foot. Subgroup analyses revealed no significant associations for children with flat foot, cross-sectional studies, or prospective studies on high arch.

Conclusions : High arch and flat-foot foot types are associated with lower extremity injuries but the strength of this relationship is low. Although FPI and visual/physical examination are methods that displayed significance, they are qualitative measures. Radiographic and NH measurements can delineate high arch foot effectively, with only anthropometric measures accurately classifying flat foot.