Background The intensity and magnitude of secondary school sports participation is increasing annually. In this population there is a high incidence of anterior cruciate ligament injury, particularly in females. Two dimensional (2D) lower limb biomechanical analysis may present an inexpensive and clinically applicable way to evaluate biomechanical risk factors for knee injury in this population.

Objective To compare 2D landing biomechanics of early adolescent male and female athletes in their first year of secondary school.

Design Cross-sectional.

Setting Secondary school gymnasium.

Participants 42 male (age=13.06±2.5 years) and 50 female (age=13.09±2.3 years) early adolescent secondary school athletes. All participants were fully engaged in sports and free from injury at the time of testing.

Interventions Each participant performed 3 drop vertical jump (DVJ) trials. Frontal and sagittal plane knee angles were recorded by video cameras for the dominant and non-dominant limbs.

Main Outcome Measurements The categorical independent variables were gender (male vs female) and limb (dominant vs non-dominant). Knee flexion angle and frontal plane knee angle (FPKA) measured at the video frame prior to initial contact (pre-IC) were used as dependant variables. Peak knee flexion and peak FPKA following IC were also used as dependant variables.

Results There was a significant main effect for gender. Females demonstrated greater FPKA pre-IC (P<.01; mean difference=2.32°±0.45°) and peak FPKA following IC (P<.01; mean difference=9.82°±1.26°). Females displayed significantly less knee flexion pre-IC (P<.01; mean difference=3.22°±0.95°), but no differences were observed for peak knee flexion following IC (P>.05).

Conclusions The results of the current investigation show that early adolescent female athletes demonstrate less desirable jump landing biomechanical profiles than their male counterparts, which may have implications for knee injury. 2D analysis could be utilised in this population to identify those at an increased risk of injury.