Background: Compared with male athletes, female athletes demonstrate
increased dynamic valgus angulation of the knee during landing from a jump,
although prior to maturation male and female athletes have similar forces and
motions about the knee when they land from a jump. Our hypothesis was that
musculoskeletal changes that accompany maturation result in poor neuromuscular
control of the knee joint in female athletes.
Methods: One hundred and eighty-one middle-school and high-school
soccer and basketball players—100 girls and eighty-one
boys—participated in the study. Dynamic control of the knee joint was
measured kinematically by assessing medial knee motion and the lower-extremity
valgus angle and was measured kinetically by assessing knee joint torques; the
values were then compared between female and male athletes according to
maturational stage. Lower-extremity bone length was measured with
three-dimensional kinematic analysis.
Results: Following the onset of maturation, the female athletes
landed with greater total medial motion of the knees and a greater maximum
lower-extremity valgus angle than did the male athletes. The girls also
demonstrated decreased flexor torques compared with the boys as well as a
significant difference between the maximum valgus angles of their dominant and
nondominant lower extremities after maturation.
Conclusions: After girls mature, they land from a jump differently
than do boys, as measured kinematically and kinetically.
Clinical Relevance: Following the onset of the pubertal growth
spurt, female athletes change the way that they land from a jump. This change
may be due to decreased neuromuscular control of the knee and may explain why
the risk of anterior cruciate ligament injury is higher in girls than it is in
boys. The measures of neuromuscular control of the knee used in this report
may be employed to monitor athletes and to direct appropriate new
interventions to athletes at high risk for injury.