A 2D video-based assessment is associated with 3D biomechanical contributors to dynamic knee valgus in the coronal plane

Abstract

Introduction: Adolescent athletes involved in sports that involve cutting and landing maneuvers have an increased risk of anterior cruciate ligament (ACL) tears, highlighting the importance of identifying risky movement patterns such as dynamic knee valgus (DKV). Qualitative movement screenings have explored two-dimensional (2D) scoring criteria for DKV, however, there remains limited data on the validity of these screening tools. Determining a 2D scoring criterion for DKV that closely aligns with three-dimensional (3D) biomechanical measures will allow for the identification of poor knee position in adolescent athletes on a broad scale. The purpose of this study was to establish a 2D scoring criterion that corresponds to 3D biomechanical measures of DKV.

Methods: A total of 41 adolescent female club volleyball athletes performed a three-task movement screen consisting of a single-leg squat (SLS), single-leg drop landing (SLDL), and double-leg vertical jump (DLVJ). A single rater scored 2D videos of each task using four criteria for poor knee position. A motion capture system was used to calculate 3D joint angles, including pelvic obliquity, hip adduction, knee abduction, ankle eversion, and foot progression angle. Receiver operating characteristic curves were created for each 2D scoring criterion to determine cut points for the presence of movement faults, and areas under the curve (AUC) were computed to describe the accuracy of each 2D criterion compared to 3D biomechanical data.

Results: 3D measures indicated knee abduction angles between 2.4°-4.6° (SD 4.1°-4.3°) at the time point when the center of the knee joint was most medial during the three tasks. AUCs were between 0.62 and 0.93 across scoring items. The MEDIAL scoring item, defined as the knee joint positioned inside the medial border of the shoe, demonstrated the greatest association to components of DKV, with AUCs ranging from 0.67 to 0.93.

Conclusion: The MEDIAL scoring criterion demonstrated the best performance in distinguishing components of DKV, specifically pelvic obliquity, hip adduction, ankle eversion, and foot progression. Along with the previously published scoring definitions for trunk-specific risk factors, the authors suggest that the MEDIAL criterion may be the most indicative of DKV, given an association with 3D biomechanical risk factors.

Keywords: anterior cruciate ligament injury; injury prevention; motion capture; qualitative movement analysis; video analysis.

Figure 1

Marker set diagram. CLAV: clavicle notch, XP: xiphoid process, T1/T10: 1st and 10th thoracic vertebrae, ASIS: anterior superior iliac spine, SACR: sacrum, THC: rigid thigh cluster, LKN/MKN: lateral and medial femoral epicondyle, SHC: rigid shank cluster, LANK/MANK: lateral and medial malleolus, 5MET: 5th metatarsal head, TOE: 2nd metatarsal head, HEEL: midline of the hindfoot at approximately the same height as the TOE marker.

Figure 2

(A) SHOE: knee joint center inside the midline of the shoe. MEDIAL: Knee joint center inside the medial border of the shoe. (B) LINE: Angle from hip to knee to ankle is less than 180°. (C) DIFF: Distance between the medial knee and lateral hip increases (single-leg tasks, top row) or distance between the knee joint centers decreases (double-leg task, bottom row).

Figure 3

Video scoring sheet used to identify 2D movement faults per task.