Analysis of Genu Varum in Young Male Professional Soccer Players

Background: Bowlegs (Genu varum) are well-known leg axis deformities in adult soccer players and are associated with an increased risk of knee osteoarthritis. The time of onset of genu varum is unknown. Purpose: To analyze the static and dynamic leg axis in young professional soccer players from childhood to adolescence. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Leg axes of 168 male professional soccer players (336 legs) from 8 age groups (U12-U21) were analyzed. Static and dynamic mechanical femorotibial axis angles (MAAs) were determined using a noninvasive motion analysis system allowing both legs to be evaluated individually. Additionally, the intercondylar and intermalleolar distances were measured. Statistical analyses were performed using a linear mixed model including the variables of age, playing position, shooting leg, and body mass index (BMI). Results: A significant increase in varus alignment for static and dynamic MAA was found with age. Players of the teams U17, U19, and U21 had significantly higher static MAAs (greater varus) compared with the youngest players (U12). The deviation in the dynamic MAA could be observed starting from the U15 onward. In all age groups, the dynamic MAA was significantly lower than the static MAA. No significant association was found for static or dynamic MAA with BMI, playing position, or shooting leg. Conclusion: In this study, the degree of static and dynamic varus alignment was significantly associated with increasing age. On the basis of the study's findings, it is believed that preventive training methods particularly focusing on vulnerable age groups should be tested for efficacy.