Poor static balance is a risk factor for non-contact anterior cruciate ligament injury

This prospective study aimed to investigate the relationship between static balance and the incidence of non-contact anterior cruciate ligament (ACL) injury in female high school athletes.

This study included 276 female high school handball or basketball players. At the time of admission, each subject's static balance was measured with a gravicorder, and the incidence of non-contact ACL injury was investigated in the 3 years until the student graduated. The measured parameters of postural sway were locus length per time (the distance that a center of gravity of the foot pressure moves per second) and environmental area (AR: the area surrounded by the integumentary covering of the trace of the center of gravity). Twenty-seven players (9.8%) experienced an ACL injury during the 3-year observation period. Twenty-four injured players sustained a non-contact injury and three injured players sustained a contact injury. In this study, the three contact injury players were excluded. We compared the differences in the static balance between injured and uninjured players.

The locus length per time was significantly longer in injured than in uninjured players (p = 0.046). Though there was no statistically significant difference between the two groups in AR (p = 0.190), AR tended to be larger in the ACL injured group.

This result shows that poor static balance is a risk factor for non-contact ACL injury.