Does Medial Knee Position Reflect Dynamic Knee Valgus? Comparing Kinematic Timing and Magnitude During a Three-Task Movement Screen.

Abstract

Background: Movement screenings have been implemented to mitigate the rising incidence of knee injuries in youth athletes. Despite interest, it remains unclear how well two-dimensional risk assessments reflect the multi-planar contributors to dynamic knee valgus.

Purpose: The purpose of this study was to evaluate how medial knee collapse corresponds to dynamic knee valgus multi-planar components by comparing timing and magnitude of knee abduction and medial knee position.

Study design: Cross-sectional study.

Methods: Adolescent female volleyball players completed a three-task movement screen captured with a 3D motion capture system consisting of a single-leg squat, single-leg drop landing, and double-leg vertical jump. Position and timing of most medial knee position (MMK) and maximum knee abduction angle (MKA) were extracted for each task, as well as components of dynamic knee valgus at those timepoints of interest. Kinematic variables, timings and positions at MMK and MKA were compared using Wilcoxon signed-rank tests.

Results: Most medial knee position occurred prior to maximum knee abduction angle for the single-leg drop landing (31.56% vs 37.40%) and the double-leg vertical jump (Loading phase: 28.48% vs 51.36%; Landing phase: 18.36% vs 57.68%). During the single-leg squat, participants demonstrated increased pelvic rise (MMK: 0.50° vs MKA: -1.52°) and greater hip adduction (MMK: 13.86° vs MKA: 10.95°) at the point of most medial knee position. Additionally, during the double-leg vertical jump task, the hip was less externally rotated at the point of most medial knee position (Loading phase: MMK: 2.52° vs MKA: -0.93°; Landing phase: MMK: -1.11° vs MKA: -3.81°).

Conclusion: Across all tasks, tibial rotation was more external when the knee was at its most medial position. Medial knee collapse measured in the 2D plane does not necessarily translate to components of dynamic knee valgus observed in 3D, though 2D peak knee medialization provides a clinically accessible tool to assess broader movement patterns of the lower extremity whenever 3D analysis is not feasible.

Level of evidence: Level 3.