Influence of the helical and six available Cardan sequences on 3D ankle joint kinematic parameters.

Cardan/Euler and helical angles are the popular methods of quantifying angular kinematics. Cardan angles are sequence dependent and crosstalk can influence the kinematic calculations. The International Society of Biomechanics (ISB) recommends a sagittal, coronal, and then transverse (XYZ) sequence of rotations, although it has been proposed that when calculating rotations outside of the sagittal plane, this may not be the most appropriate method. This study investigated the influence of the helical and six available Cardan sequences on three-dimensional (3D) ankle joint kinematics. Kinematic data were obtained using an eight-camera motion analysis system as participants ran at 4.0 m/s +/- 5%. Repeated measures ANOVAs were used to compare kinematic parameters, and intraclass correlations were employed to identify evidence of crosstalk across planes. The results indicate that in the transverse and coronal planes, peak angle and range of motion values using the YXZ and ZXY sequences were significantly greater than the other sequences. Furthermore, utilization of YXZ and ZXY sequences was associated with the strongest correlations from the sagittal plane, and the XYZ sequence was found to be associated with the lowest correlations. It appears that for the representation of 3D ankle joint kinematics, the XYZ sequence is associated with minimal planar crosstalk and as such its use is encouraged.