ABSTRACT
Dynamic knee valgus is considered a risk factor for anterior cruciate ligament (ACL) injuries. This study identified how knee in distance (KID) and hip out distance (HOD) affect one’s lateral trunk lean (LTL). The results were also tested for reliability. Fifteen female basketball players (30 legs) from a university participated in this study. The participants performed single-leg squats by bending the knee of the supporting leg to 60°. The trials were recorded using a video camera. The KID, HOD, and LTL were measured with two-dimensional images using the Dartfish software, which measured the maximal knee valgus. The Pearson’s correlation coefficient was used to measure the correlation between dynamic knee valgus (KID and HOD) and LTL. Additionally, the Interclass Correlation Coefficient (ICC) was used to measure the reliability of the KID, HOD, and LTL data sets. The statistical significance was established at a level of p<0.05. Results showed that the KID and LTL had a significantly negative correlation, measured at r=-0.227, p<0.05. The ICC (2.1) values were: 0.83 for HOD, 0.99 for KID, and 0.96 for LTL; while the ICC (1.2) values were: 0.86 for HOD, 0.83 for KID, and 0.85 for LTL. The two-dimensional analysis technique revealed that the values were highly reliable. In sum, dynamic knee valgus had a negative correlation with LTL during single-leg squats. Therefore, it was suggested that the factors of dynamic knee valgus might be evaluated using LTL on two-dimensional screening test.
ABSTRACT
Dynamic knee valgus is considered a risk factor of non-contact anterior cruciate ligament (ACL) injury. To identify athletes at a higher risk, we developed a two-dimensional (2D) video-based screening test that determines hip abductor function as well as dynamic hindfoot and knee valgus. The purpose of this study was to validate the accuracy of the indices for dynamic knee valgus derived knee-in distance (KID) and hip-out distance (HOD) from the 2D-video.Twenty healthy university students agreed to participate in this study. Subjects were asked to step off a 30-cm box and land on one leg. This procedure was recorded simultaneously using a 2D video camera in the frontal plane and the Vicon motion capture system. Pearson's correlations examined associations between KID, KID normalized by height (KID/H), HOD, as well as HOD normalized by height (HOD/H) and 3D-valgus (knee valgus) or 3D-IR (tibial internal rotation).Significant correlations were found between the KID and 3D-valgus (r=0.72, p<0.01) and KID/H and 3D-valgus (r=0.73, p<0.01). Associations were not significant between KID and 3D-IR (r=0.08) and between KID/H and 3D-IR (r=0.03). A positive moderate correlation between HOD and 3D-valgus (r=0.46, p<0.05) and HOD/H and 3D-valgus (r=0.50, p<0.05), as well as a negative moderate correlations between HOD and 3D-IR (r=-0.52, p<0.05) and between HOD/H and 3D-IR (r=-0.51, p<0.05) were also observed.We conclude that KID is a reliable alternative for the 3D-valgus and the HOD is for the 3D-valgus and tibial external rotation.