Differences in lower limb transverse plane joint moments during gait when expressed in two alternative reference frames

Lower limb transverse plane internal joint moments during gait: (a) expressed in the distal segment AF and (b) expressed in the LF. Solid line: right side, dashed line: left side. Shaded area indicates the standard deviation band about the group mean.

The components of the external moment in the transverse plane, expressed in the LF, at each of the lower limb joints during gait: (a) the resultant ground reaction force acting at a distance to the joint centre (external GRF moment); (b) the free moment of rotation acting about a vertical axis through the centre of pressure (external Free moment); (c) the external GRF and Free moments combined excluding the component of the external moment due to segment weight and inertia (external Total moment). The external Free moment and the external GRF moment can be seen to have complimentary effects at the ankle joint but opposing effects at the hip and knee joints. Solid line: right side, Dashed line: left side. Shaded area indicates the standard deviation band about the group mean.

The components of the external moment in the transverse plane, expressed in the distal segment AF, at each of the lower limb joints during gait: (a) the resultant ground reaction force acting at a distance to the joint centre (external GRF moment); (b) the free moment of rotation acting about a vertical axis through the centre of pressure (external Free moment); (c) the external GRF and Free moments combined excluding the component of the external moment due to segment weight and inertia (external Total moment). The external Free moment and the external GRF moment can be seen to have complimentary effects at all lower limb joints. Solid line: right side, dashed line: left side. Shaded area indicates the standard deviation band about the group mean.

Coronal view of the foot AF. Point A depicts the bi-malleolar axis, point B depicts the bisection of the posterior calcaneus and AJC indicates the ankle joint centre. Note the dependency of the foot AF vertical (z) axis on the alignment of the posterior calcaneus which medially inclines the foot AF transverse plane with respect to the LF for an ‘everted’ rearfoot.

Orientation of the resultant GRF vector in the LF sagittal plane for the left lower limb during (a) initial stance and (b) terminal stance. The GRF vector is indicated by the thick solid line.

Orientation of the resultant GRF vector projected into (a) the LF transverse plane, (b) the femoral AF transverse plane and (c) the tibial (proximal) AF transverse plane during initial stance and terminal stance for the left lower limb. The projected GRF vector is indicated by the thick solid line. Note that LF (HJC) and LF (KJC) represent the translated LF such that the origin is located at the HJC and KJC respectively.

‘Invertor-evertor’ internal ankle joint moment during gait expressed in (a) the foot AF and (b) the LF. The orientation of the projected GRF vector in the frontal plane of both the foot AF and LF during mid stance for the left foot is also displayed.

Orientation of the resultant GRF vector projected into the LF transverse plane at the AJC during (a) initial stance and (b) terminal stance for the left foot. The projected GRF vector is indicated by the thick solid line.

Orientation of the resultant GRF vector projected into the foot AF transverse plane at the AJC during (a) initial stance, (b) mid stance for the left foot (varus alignment) and (c) mid stance for the left foot (valgus alignment). The projected GRF vector is indicated by the thick solid line.