Comparison of 2-Dimensional Measurement Techniques for Predicting Knee Angle and Moment During a Drop Vertical Jump

Abstract

Objective To determine the association of two dimensional (2D) video-based techniques and three-dimensional (3D) motion analysis to assess potential knee injury risk factors during jump landing. Design Observational study Setting Research Laboratory Participants Thirty-six female athletes in cutting and pivoting sports. Assessment Athletes performed a drop vertical jump during which movement was recorded with a motion analysis system and a digital video camera positioned in the frontal plane. Main Outcome Measures The 2D variables were the frontal plane projection angle (FPPA), the angle formed between thigh and leg, and the knee:ankle separation ratio, the distance between knee joints divided by the distance between ankles. The 3D variables were knee abduction angle and external abduction moment. All variables were assessed at peak knee flexion. Linear regression assessed the relationship between the 2D and 3D variables. In addition, intraclass correlation coefficients determined rater reliability for the 2D variables and compared the 2D measurements made from digital video to the same measurements from the motion analysis. Results The knee:ankle separation ratio accounted for a higher variance of 3D knee abduction angle (r2 =0.350) and knee abduction moment (r2=0.394) when compared to the FPPA (r2=0.145, 0.254). The digital video measures had favorable rater reliability (ICC:0.89–0.94) and were comparable to the motion analysis system (ICC≥0.92). Conclusion When compared to the FPPA, the knee:ankle separation ratio had better association with previously cited knee injury risk factors in female athletes. The 2D measures have adequate consistency and validity to merit further clinical consideration in jump landing assessments.

Physiotherapists Can Identify Female Football Players With High Knee Valgus Angles During Vertical Drop Jumps Using Real-Time Observational Screening

“…Interestingly, this value corresponded closely to the valgus angles for participants displaying poor control in the current study. Another study 24 compared the frontal plane projection angle and knee separation distance measured from 2-D video recordings and 3-D motion analysis and reported intraclass correlation coefficients of 0.89 to 0.97, demonstrating higher agreement than that reported in the current study. This is logical, as video analysis permits a more standardized and detailed assessment than real-time observational screening.…”

“…Higher agreement has been found for vertical drop-jump assessments, with agreement of 88% to 93% and corresponding kappa coefficients of 0.75 to 0.85 in 1 study 10 and intraclass correlation coefficients of 0.89 and 0.92 in another. 24 However, the drop-jump assessments in these studies were based on video reviews, and only 1 study 31 has investigated real-time assessment of knee kinematics during a vertical drop-jump task. Stensrud et al 31 reported good agreement between realtime visual evaluation of knee control during a vertical drop-jump landing task and 2-D video analysis of knee valgus.…”

“…However, reliable visual criteria are necessary to standardize ratings and to ensure adequate reliability. The reliability of visual assessments of frontal plane knee motion using 2-D video recordings has been investigated during single-leg squats 1,7 and vertical drop jumps, 10,24 with varying results. For single-leg squats, the percentage agreement between raters has been reported to be 41% to 96%, with kappa coefficients ranging from 0.00 to 0.92.…”

“…The relationship between 3-D motion analysis and 2-D video reviews of vertical drop jumps has been evaluated, with moderate to good correlations reported. 10,22,24 Other studies have attempted to develop clinic-based algorithms to predict high knee abduction moments during dropjump landings. [25][26][27] Real-time observational screening represents an easy and low-cost method for assessing knee valgus during a drop-jump task.…”

“…simplistic screening methods. 10,22,24,29 For example, the assessment of frontal plane knee motion using 2-dimensional video (2-D) during a drop-jump landing task is commonly used clinically. The relationship between 3-D motion analysis and 2-D video reviews of vertical drop jumps has been evaluated, with moderate to good correlations reported.…”