Orientation of lower limb joint-axes during gait in children with cerebral palsy

Rationale: One of the most common disabilities in childhood is Cerebral Palsy (CP). Musculoskeletal problems such as spasticity and joint deformities are frequently seen within CP patients. As a consequence, joint movement axes are rotated relative to each other in the transverse plane. The malalignment of rotation axes leads to deviated gait patterns and limited self-mobility in approximately 50% of the children with CP.
Robotic devices can provide gait training with intensive, controlled, repetitive, and goal-oriented movements with promising results for adults and children. Within the current robotic devices, the axes of rotation for flexion around the ankle, knee and hip are nearly perfectly parallel aligned in the transversal plane. Therefore, they are not optimal for children with CP with joint deformities. A possible solution could be adjustable axes of rotations within the design of the robotic devices. In order to define the minimally needed ranges for adaptable axes of rotation, it is important to determine the orientation of the lower limb joint axes with respect to the walking direction in children with CP with joint deformities.
Objective: The primary objective of this research is to identify the orientation of the ankle, knee and hip joint axes of rotation (flexion-extension) with respect to the walking direction during gait and standing in children with CP. The secondary objective is to determine the correlation between the orientation of the these joint axes during gait and standing in children with CP. In addition, we will determine the correlation between the tibia and femoral torsion as measured during the clinical examination, the femoral anteversion angle from x-ray and the orientation of the axes during gait.
Study design: Retrospective cross-sectional study.
Study population: CP patients, Gross Motor Function Classification System (GMFCS) level II-IV, 8 - 12 years old at time of 3D Gait Analysis (3DGA).
Intervention: not applicable.
Main study parameters/endpoints: The main study parameter is the mean and variation of the orientation the lower limb joint axes with respect to the walking direction during gait (during the stance and swing phase separately) and standing from 3DGA.
Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Patients have already had the 3DGA and all clinical tests for clinical purposes. Participating in the study does not involve any procedures. Therefore, no risks are identified and no burden is associated with participation. Patients do not directly benefit from participating but participation does increase knowledge about the orientation of the lower limb joint axes with respect to the walking direction in children with CP with joint deformities.

It is hypothesized that the orientation of the lower limb joints are not parallel to the walking direction and that a standing measure is highly correlated with the orientation during the standing, load bearing, phase of the gait cycle.

Retrospective data analysis; no time points.