Longitudinal sex differences during landing in knee abduction in young athletes

Abstract

Purpose: The objective of this study was to determine whether biomechanical and neuromuscular risk factors related to abnormal movement patterns increased in females, but not males, during the adolescent growth spurt.

Methods: A total of 315 subjects participated in two testing sessions approximately 1 yr apart. Male and female subjects were classified on the basis of their maturation status as pubertal or postpubertal. Three trials of a drop vertical jump (DVJ) were collected. Maximum knee abduction angle and external moments were calculated during the DVJ deceleration phase using a three-dimensional motion analysis system. Changes in knee abduction from the first to second year were compared among four subject groups (female pubertal, female postpubertal, male pubertal, and male postpubertal).

Results: There were no sex differences in peak knee abduction angle or moment during DVJ between pubertal males and females (P > 0.05). However, pubertal females increased peak abduction angle from first to second year (P < 0.001), whereas males demonstrated no similar change (P = 0.90) in the matched developmental stages. After puberty, the peak abduction angle and moment were greater in females relative to males (angle: female -9.3° ± 5.7°, male -3.6° ± 4.6°, P < 0.001; moment: female -21.9 ± 13.5 N·m, male -13.0 ± 12.0 N·m, P = 0.017).

Conclusions: This study identified, through longitudinal analyses, that knee abduction angle was significantly increased in pubertal females during rapid adolescent growth, whereas males showed no similar change. In addition, knee abduction motion and moments were significantly greater for the subsequent year in young female athletes, after rapid adolescent growth, compared with males. The combination of longitudinal, sex, and maturational group differences indicates that early puberty seems to be a critical phase related to the divergence of increased anterior cruciate ligament injury risk factors.

Figures

Figure 1

Bland-Altman plot demonstrating the agreement between the change in length measured with the stadiometer and segment motion analysis. Solid line represents the mean difference between the change in height – change in segment lengths. Less than five percent of the 315 cases fall outside the 95% confidence interval.

Figure 2

Ensemble average plot of knee flexion angle (+/- one standard deviation, gray shaded area) throughout the stance phase of the drop vertical jump. The stance phase begins with initial ground contact (0% stance) and ends with toe off (100% stance).

Figure 3

Ensemble average plot of knee abduction angle (+/- one standard deviation, gray shaded area) throughout the stance phase of the drop vertical jump. The stance phase begins with initial ground contact (0% stance) and ends with toe off (100% stance).

Figure 4

Ensemble average plot of knee abduction moment (+/- one standard deviation, gray shaded area) throughout the stance phase of the drop vertical jump. The stance phase begins with initial ground contact (0% stance) and ends with toe off (100% stance).