Prevalence of bowlegs among child and adolescent soccer players

Objective: Little is known about the interactions of sports-related demands and human body, in particular on musculoskeletal features, during growth. Focusing on the relationship between soccer and lower limb alignment, we examined the hypothesis that varus knee deviation is more prevalent among high-performance pediatric and adolescent soccer players. Design: Cross-sectional study with focused sampling. Setting: First league sports clubs. Participants: 106 male child/adolescent soccer players aged 10 to 21 years and 68 age-matched tennis players. Interventions: All athletes completed a demographic questionnaire and underwent physical examinations, which included height, weight, generalized laxity, knee, ankle, foot and spine axis, hip range of motion, tibial torsion, Q angle, foot navicular height, and progression angle. Main Outcome Measurement: Varus/valgus axis was determined by the intercondylar intermalleolar distance while standing. Soccer and tennis players were compared on knee axis and other outcome variables by analysis of covariance, adjusting for age and by t-tests within age groups. Results: A significantly higher prevalence of knee varus was found among the soccer players compared to that among the tennis players. The difference in intracondylar distance was statistically significant after the age of 13 years (P < 0.001). In addition, compared to tennis players, soccer players had higher foot arches, decreased hip external rotation and increased external tibial torsion. Conclusions: Varus knee axis deviation was more common among children and adolescent soccer players than among tennis players. The prevalence was more pronounced among players aged 13 years or older. Further research is needed to explore the rationale of this phenomenon.