title: Association between foot type and lower extremity injuries: systematic literature review with meta-analysis.
abstract: METHODS
  Systematic literature review with meta-analysis.
  
  
  OBJECTIVE
  To investigate the association between nonneutral foot types (high arch and flatfoot) 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 Dissertations and Theses), Google Scholar, and the 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 ratio (OR) and standardized mean difference (SMD) results for meta-analysis.
  
  
  RESULTS
  Twenty-nine studies were included for meta-analysis. A significant association between nonneutral foot types and lower extremity injuries was determined (OR = 1.23; 95% confidence interval [CI]: 1.11, 1.37; P<.001). Foot posture index (OR = 2.58; 95% CI: 1.33, 5.02; P<.01) and visual/physical examination (OR = 1.17; 95% CI: 1.06, 1.28; P<.01) were 2 assessment methods using distinct foot-type categories that showed a significant association with lower extremity injuries. For foot-assessment methods using a continuous scale, measurements of lateral calcaneal pitch angle (SMD, 1.92; 95% CI: 1.44, 2.39; P<.00001), lateral talocalcaneal angle (SMD, 1.36; 95% CI: 0.93, 1.80; P<.00001), and navicular height (SMD, 0.34; 95% CI: 0.16, 0.52; P<.001) showed significant effect sizes in identifying high-arch foot, whereas the navicular drop test (SMD, 0.45; 95% CI: 0.03, 0.87; P<.05) and relaxed calcaneal stance position (SMD, 0.49; 95% CI: 0.01, 0.97; P<.05) displayed significant effect sizes in identifying flatfoot. Subgroup analyses revealed no significant associations for children with flatfoot, cross-sectional studies, or prospective studies on high arch.
  
  
  CONCLUSIONS
  High-arch and flatfoot foot types are associated with lower extremity injuries, but the strength of this relationship is low. Although the foot posture index and visual/physical examination showed significance, they are qualitative measures. Radiographic and navicular height measurements can delineate high-arch foot effectively, with only anthropometric measures accurately classifying flatfoot.
  
  
  METHODS
  Prognosis, level 2a.
authors.affiliation: Physical Education and Sports Science Academic Group, National Institute of Education, Nanyang Technological University, Singapore.
authors.forename: Jasper W K
authors.initials: JW
authors.lastname: Tong
authors.forename: Pui W
authors.initials: PW
authors.lastname: Kong
mesh_terms: D005413:Flatfoot / Q000150:complications*; D005528:Foot / Q000033:anatomy & histology*; D006801:Humans; D015994:Incidence; D007869:Leg Injuries / Q000453:epidemiology* / Q000209:etiology