Hip- and knee-joint kinematics during drop landings are relevant to lower-extremity injury mechanisms. In clinical research the “gold standard” for joint kinematic assessment is 3-dimensional (3D) motion analysis. However, 2-dimensional (2D) kinematic analysis is an objective and feasible alternative.
To quantify the relationship between 2D and 3D hip and knee kinematics in single-leg drop landings and test for a set of 3D hip and knee kinematics that best predicts 2D kinematic measures during single-leg drop landings Design: Descriptive, comparative laboratory study.
31 healthy college-age women (65.5 kg [SD 12.3], 168.1 cm [SD 6.7]).
Participants performed five 40-cm single-leg landings during motion capture at 240 Hz. Multiple regressions were used to predict relationships for knee and hip between 2D frontal-plane projection angles (FPPA) and 3D measurements.
2D knee FPPA had a strong relationship with 3D frontal-plane knee kinematics at initial contact (IC) (r2 = .72), which was only minimally improved with the addition of knee sagittal-plane and hip transverse-plane positions at IC (r2 = .77). In contrast, 2D knee FPPA had a low relationship with 3D knee-abduction excursion (r2 = .06). The addition of knee sagittal-plane and hip transverse-plane motions did not improve this relationship (r2 = .14). 2D hip FPPA had a moderate relationship with 3D frontal-plane hip position at IC (r2 = .52), which was strengthened with the addition of hip sagittal-plane position (r2 = .60). In addition, hip 2D FPPA into adduction excursion had a strong association with 3D hip-adduction excursion (r2 = .70).
2D kinematics can predict 3D frontal-plane hip and knee position at IC during a single-leg landing but predict 3D frontal-plane knee excursion with far less accuracy.
Sorenson, Kernozek, and Hove are with the Dept of Health Professions, and Ragan, the Dept of Physics, University of Wisconsin–La Crosse, La Crosse, WI. Willson is with the Dept of Physical Therapy, East Carolina University, Greenville, NC.