title: How does lower leg alignment differ between soccer players, other athletes, and non-athletic controls?
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  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.
  
  
  METHODS
  Diagnostic study, Level III.
authors.affiliation: Department of Orthopaedics, University Hospitals Leuven, Weligerveld 1, 3212, Pellenberg, Belgium. william_colyn@hotmail.com.
authors.forename: William
authors.initials: W
authors.lastname: Colyn
authors.affiliation: Department of Orthopaedics, Erasmus MC University Medical Center, 's-Gravendijkwal 230, 3015 CE, Rotterdam, The Netherlands.
authors.forename: Rintje
authors.initials: R
authors.lastname: Agricola
authors.affiliation: Department of Orthopaedics, University Hospital Ghent, De Pintelaan 185, 9000, Ghent, Belgium.
authors.forename: Nele
authors.initials: N
authors.lastname: Arnout
authors.affiliation: Department of Orthopaedics, Erasmus MC University Medical Center, 's-Gravendijkwal 230, 3015 CE, Rotterdam, The Netherlands.
authors.forename: Jan A N
authors.initials: JA
authors.lastname: Verhaar
authors.affiliation: Department of Orthopaedics, Zol Genk, Schiepse Bos 6, 3600, Genk, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: Bellemans
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000842:Ankle; D000843:Ankle Joint / Q000000981:diagnostic imaging* / Q000254:growth & development; D056352:Athletes; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000254:growth & development; D056305:Genu Varum / Q000000981:diagnostic imaging* / Q000453:epidemiology; D006801:Humans; D007717:Knee; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000254:growth & development; D007866:Leg; D008297:Male; D011187:Posture; D012737:Sex Factors; D012916:Soccer; D013977:Tibia / Q000000981:diagnostic imaging* / Q000254:growth & development; D055815:Young Adult
keywords: Adaptation; Bowlegs; High-activity sports; Lower leg alignment; Soccer; Varus