Does the 2D Frontal Plane Projection Angle Predict Frontal Plane Knee Moments during Stepping, Landing, and Change of Direction Tasks?
Rachel K Straub, Christopher M Powers
PMID 36518844WHAT IT FOUND
A 2D knee angle predicts frontal plane knee moments during landing and cutting, but not stepping.
The relationship is weak to moderate, with R-squared values ranging from 12% to 45%, limiting its utility as a standalone clinical measure.
Key findings
01The 2D frontal plane projection angle significantly predicted average knee moments and moments at peak flexion during landing and cutting tasks, but failed to predict these moments during the step-down task.
02The strength of prediction was weak to moderate across all successful models, with R-squared values between 12% and 45%.
03The measure predicted increased knee valgus moments (or decreased varus moments) only during landing and change-of-direction tasks, not during stepping.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only healthy individuals, so results may not apply to patients with knee conditions like patellofemoral pain. The 2D angle was measured from a fixed camera perpendicular to the force plate; hand-held device measurements may introduce parallax error. The analysis was cross-sectional and did not link the 2D angle to actual injury occurrence. Only the deceleration or lowering phase of tasks was analyzed, excluding acceleration phases.
The easy way to misread this
Do not interpret the significant correlations as strong evidence of clinical utility. The R-squared values were weak to moderate (12% to 45%), meaning the 2D angle explains less than half the variance in knee moments for most tasks, and it completely failed to predict moments during the step-down task.