Summary

Canals are the preferential sites for failure in cortical bone and their architecture is able to dictate the mechanical behaviour of the bone: smaller and branched canals generate a high volume of bone failure even at low apparent tissue strain.

Purpose: The aim of this research was to characterize the correlation of magnetic resonance image (MRI) measurements of femoral anteversion and tibial torsion with transverse plane kinematics from the gait analysis of ten healthy and nine cerebral palsy (CP) children.

Methods: The bone morphologies of nine spastic diplegic CP and ten healthy children were obtained by analysis of 3D MRIs. Location of anatomical landmarks along the femur and tibia were detected using medical imaging software. Each point was then defined with respect to bone-embedded femoral and tibial Cartesian coordinates, allowing 3D reorientation of the bone independent of the patient position within the scanner. Femoral anteversion was defined as the angle between the femoral neck and the transcondylar plane. Tibial torsion was defined as the angle between the transcondylar axis of the proximal tibia and the bi-malleolar axis.

Three-dimensional motion of the lower limbs was measured using gait analysis. Transverse plane kinematics, including hip rotation and foot progression angles were recorded.

Results: A moderate correlation was found between femoral anteversion, and maximum and average hip rotation in CP children (0.64 and 0.65). A high correlation was also seen between tibial torsion and maximum and average values of hip rotation for CP children (0.71 and 0.74). In healthy children, the only correlation observed was between femoral anteversion and average foot progression in stance (0.75).

Discussion: In healthy children, femoral anteversion appears to influence foot progression angle, implying that this can lead to an internally rotated gait. In CP children, the correlation between femoral anteversion and hip rotation is only moderate. The interaction between different joints is more complex and the rotation of joints is determined by multiple factors. This study showed that tibial torsion also plays a role in determining hip rotation during gait.