Development of a Real-Time Single-Leg Hop Movement Quality Assessment to Identify Lower-Extremity Biomechanical Risk Factors.

Context: The single-leg hop is based solely on performance with no measure of movement quality. The purpose of this study was to (1) develop a real-time screening tool to capture single-leg functional performance and movement quality and (2) to provide preliminary validation (criterion validity) of a trained clinician's real-time movement quality assessment with 3D kinematics.

Study design: Cross-sectional.

Methods: Fifty-nine adolescent athletes volunteered (15.2 [1.1] y, 165.8 [9.2] cm, and 61.5 [13.9] kg, 51 females and 8 males). Each participant performed 3 trials of the single-leg hop on their dominant leg. A 3-dimensional inertial measurement system was used to capture knee joint kinematics. A movement quality checklist for use during a single-leg hop (movement quality single-leg hop) was developed to score biomechanical errors based on lower-extremity injury risk factors. Four criteria were developed for the checklist: (1) knee valgus, (2) foot rotation, (3) lateral trunk flexion, and (4) erect posture. An independent t test was conducted for each dependent variable (knee flexion displacement and knee abduction displacement) by each independent variable (movement category presence of (1) lateral trunk flexion, (2) knee valgus, (3) foot rotation, and (4) erect posture/sound during landing [yes or no]). The alpha level was set at α < .05 for all analyses.

Results: Knee flexion displacement was significantly decreased (P < .001, mean difference 9.40 [1.88]) and knee abduction displacement was significantly increased (P < .001, mean difference 9.41 [0.47]) for those who had knee valgus documented by the clinician. In additional, for those with visually documented erect posture/sound of landing, there was a significant decrease in knee flexion displacement (P < .001, mean difference 10.13 [2.34]).

Conclusion: The movement quality single-leg hop checklist has shown promising preliminary validation (criterion validity) for clinicians to assess movement quality. Increased knee abduction and decreased knee flexion are common risk factors associated with knee injuries and this clinician friendly real-time checklist may highlight individuals who are at risk of sustaining a knee injury.