The whole understanding of the concept of ‘overpronation’ and what association that it may or may not have with injury in runners continues to evolve. Historically ‘pronation’ was somehow evil and had to be eliminated at all costs as it was the cause of almost every injury that runners got¹. Over time it was becoming more apparent in the prospective studies that the links between excessive pronation and overuse injury was, at best, tenuous. Some data did show a weak link, but other data was showing no links. Depending on what agenda you wanted to promote you could cherry pick a few studies to support your argument. My interpretation of the body of literature at that time was that there was no link between pronation and injury or if there was, it was very weak. I think I have been bleating on about that for a good 15 yrs now and for those that are familiar with the concepts around supination resistance, know that this interpretation fueled the work on that concept. Now I sense the tide is starting to turn a little.
I previously wrote how nonsensical most of what is written about overpronation is anyway and also about a new study that did find a link between higher amounts of pronation and an overuse injury. When there are enough studies on a topic, proper formal reviews of all the studies that meet certain quality standards or eligibility criteria can be done and all the data pooled and analyzed. A couple of previous attempts at this have been done with mixed results. Now that there are more studies to add to the meta-analyses, this new review was just released in pre-publication:
Association Between Foot Type and Lower Extremity Injuries: Systematic Literature Review With Meta-analysis
Jasper W.K. Tong, Pui W. Kong
J Orthop Sports Phys Ther, Epub 11 June 2013. doi:10.2519/jospt.2013.4225
STUDY DESIGN: Systematic literature review with meta-analysis.
OBJECTIVES: 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.
CONCLUSION: 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.
This was a well done and very thorough meta-analysis. They also address the issues I identified here on the different measures of ‘pronation’ and that may affect the results of an individual study depending on which measure they choose to use. The pooling of the data from a number of studies clearly shows that there is a link between ‘overpronation’ and overuse injury, even though strength of that risk is low, it is statistically significant. The pooled data did not include the new study I wrote about here (probably due to the timelines of publication between the two publications), but if they had it would have made the relationship stronger. I am also aware of another similar systematic review that has been done and not yet published. My understanding is that its results will be similar to the above study.
As always, I go where the evidence takes me until convinced otherwise and this evidence above is moving my views somewhat on overpronation.
¹In some recent lectures I have been facetiously making a link between ‘overpronation’ and infertility issues …. just to make a point! I will write about that another time!
Tong JW, & Kong PW (2013). Association Between Foot Type and Lower Extremity Injuries: Systematic Literature Review With Meta-analysis. The Journal of orthopaedic and sports physical therapy PMID: 23756327