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.