Summary

A 3-year prospective cohort study to evaluate risk factors for non-contact anterior cruciate ligament injury was conducted using 171 15-year-old female high school basketball players. 14 knees (13 players) of them injured non-contact ACL tear during the 3 years. Greater body mass index and muscle strength of hip abduction were identified as the risk factors for non-contact ACL injure.

Abstract

Purpose

To prospectively evaluate risk factors for non-contact anterior cruciate ligament (ACL) injury in Japanese female high school basketball players. We hypothesized that female high school basketball players suffering non-contact ACL injury would demonstrate weaker hip abductor and knee flexor muscle strength and poor static balance, when compared to those without injury.

Methods

Between 2009 and 2011, 195 new female high school basketball players underwent detailed examinations for various parameters that were documented at their first-year of high school. The parameters assessed were height (cm), body weight (kg), body mass index (kg/m2), anterior knee laxity (mm), general joint laxity (point), femoral anteversion (degree), navicular drop (mm), muscle strength of knee flexion (Nm/kg), extension (Nm/kg), and hip abduction (Nm/kg) and static balance. All ACL injury that occurred during these 3 year were recorded. The data were analyzed using SPSS for Windows 23.0. The parameters were compared using the Student t-test. Parameters with P values < 0.2 were considered independent variables by logistic regression analysis (simultaneous). The level of significance for all statistical analysis was set at a= 0.05.
Result: Of the 195 players, 24 were excluded because they either had a history of ACL injury or could not complete the study. The remaining 171 players were observed during the 3 years, from start of high school until graduation. 16 knees (15 players) occurred ACL injury. Two of the ACL injury were contact injury, whereas the remaining 14 were non-contact ACL injuries. Nine players were injured during the games, seven were injured during practices. The parameters were measured as follows for the ACL injury group and control group respectively: height, 161.3±6.7 and 162.0±5.7cm, P=0.63; body weight, 57.5±7.8 and 55.4±6.2kg, P=0.22; body mass index, 22.1±1.8 and 20.1±2.7, P=0.17; anterior knee laxity, 4.0±1.0 and 3.8±1.1mm, P=0.54; general joint laxity, 1.8±1.3 and 2.7± 2.2 point, P=0.03; femoral anteversion, 16.2±3.7 and 16.7±3.3 degree, P=0.60; navicular drop, 8.5±6.2 and 8.0±3.3 mm, P=0.78; muscle strength of knee flexion, 0.97±0.27 and 0.89±0.20 Nm/kg, P=0.17; muscle strength of knee extension, 1.73±0.39 and 1.58±0.35 Nm/kg, P=0.14; muscle strength of hip abduction, 1.42±0.32 and 1.26±0.24 N, P=0.02; locus length per time, 1.35±0.39 and 1.16±0.26 cm/s, P=0.09; a d environmental area, 2.62±1.64 and 2.20±1.22 cm2, P=0.37. Body mass index (P=0.008, 95% CI, 0.517-0.904) and muscle strength of hip abduction (P=0.032, 95%CI, 0.002-0.477) were found to be independent risk factors in logistic regression analysis.
Conclusion; We found that greater body mass index and muscle strength oh hip abduction were risk factors for non-contact ACL injury.