Spherical angular analysis for pelvis coordination assessment on modified gait

This study presents and applies 3D spherical angular analysis in relation with 2D polar coordinates to assess anatomic pelvic movement on modified gait, namely stiff knee (SKG) gait and slow running (SR) comparing with normal gait (NG). Subject specific analysis was performed of an adult healthy male based on inverse kinematics from in vivo and noninvasive capture at human movement lab of reflective markers position from pelvis anatomical selected points with Qualisys camera system during a complete stride of NG, SKG and SR. Radial distance (R), pitch (ψ) and azimuth (λ) angular phases were computed from pelvic angle-angle diagrams (θ_T, θ_C, θ_S) at transverse (T), coronal (C) and sagittal (S) planes, and angular phase (ϕ) and planar radial distance (r) polar coordinates computed from pelvic angle-angle diagrams projections at cartesian planes (θ_T, θ_C), (θ_T, θ_S), (θ_C, θ_S). Average radial distances and phase standard deviation were assessed on spherical and polar coordinates.