How does lower leg alignment differ between soccer players, other athletes, and non-athletic controls?

Purpose The influence of type and intensity of sports during growth on knee alignment was investigated. The second aim was to ascertain whether the distal femur or proximal tibia contribute most to knee alignment. Also, the influence of field position and leg dominancy on knee alignment in soccer players was audited. Methods Standardized full-leg standing digital radiographs were obtained from 100 males and 100 females on which 8 different alignment parameters were measured. Participants were questioned on their sports activities during different stages of growth. Sports activities were graded according to the Tegner score. Results The mean (±SD) hip–knee–ankle angle (HKA) was significantly lower ( p < 0.001) in high-activity male athletes (−2.8° ± 2.4°) than in low-activity male athletes (−0.9° ± 1.9°). No differences in HKA were observed between different activity levels in females. Males who practiced soccer between 10–12 years and 15–17 years had, in turn, a lower HKA than athletes practicing other high-activity sports in these age categories (mean difference ≥1.2°, p ≤ 0.046). The most contributing factor for the varus alignment in male soccer players was a lower medial proximal tibial angle (MPTA). Conclusion High-activity sports participation during youth is associated with varus alignment at the end of growth in males. The most pronounced bowlegs were observed in male soccer players, and this was primarily determined by the proximal tibia. Adjustments in loads applied to the knees during skeletal growth in males might prevent the development of varus alignment and associated pathology, but further studies are required. Level of evidence Diagnostic study, Level III.