VALIDATION OF A TWO-DIMENSIONAL MOTION ANALYSIS TECHNIQUE FOR QUANTIFYING DYNAMIC KNEE VALGUS DURING A DROP LANDING BY COMPARISONS TO DATA FROM THREE-DIMENSIONAL ANALYSIS / 体力科学

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.

ASSOCIATION BETWEEN HIP AND HINDFOOT DYNAMIC ALIGNMENT AND DYNAMIC KNEE VALGUS IN HIGH SCHOOL FEMALE BASKETBALL PLAYERS / 体力科学

Dynamic knee valgus is considered a risk factor of noncontact ACL injuries. The aim of this study was to determine the association between hip and hindfoot dynamic alignment and dynamic knee valgus.This cross-sectional study involved 88 high school female basketball players (175 legs). Subjects performed single-leg squatting and drop landing which provided a hip-out distance (HOD) and a knee-in distance (KID) via 2D video images. Hip and hindfoot dynamic alignment was evaluated by a dynamic Trendelenburg test (DTT) and a heel-floor test (HFT), respectively, during squatting and landing.The DTT-positive group (dynamic hip mal-alignment with lower non-weightbearing pelvis) demonstrated greater HOD and KID values for both squatting (p＜0.001) and landing (p＜0.001) than the DTT-negative group. The HFT-positive group (5^o or greater hindfoot valgus) demonstrated greater KID values for both squatting (p＜0.01) and landing (p＜0.001), but smaller HOD value for squatting (p＜0.01) than the HFT-negative group.In conclusion, dynamic hip mal-alignment may be associated with both greater HOD and KID, but hindfoot valgus only with greater KID.