Multi-segment foot kinematics during gait in children with spastic cerebral palsy

Background: Foot deformities (e.g. planovalgus and cavovarus) are very common in children with spastic cerebral palsy (CP), with the midfoot often being involved. Dynamic foot function can be assessed with 3D gait analysis including a multi -segment foot model. Incorporating a midfoot segment in such a model, allows quantification of separate Chopart and Lisfranc joint kinematics. Yet, midfoot kinematics have not previously been reported in CP. Research questions: What is the difference in multi -segment kinematics including midfoot joints between common foot deformities in CP and typically -developing feet? Methods: 103 feet of 57 children with spastic CP and related conditions were retrospectively included and compared with 15 typically -developing children. All children underwent clinical gait analysis with the Amsterdam Foot Model marker set. Multi -segment foot kinematics were calculated for three strides per foot and averaged. A k -means cluster analysis was performed to identify foot deformity groups that were present within CP data. The deformity type represented by each cluster was based on the foot posture index. Kinematic output of the clusters was compared to typically -developing data for a static standing trial and for the range of motion and kinematic waveforms during walking, using regular and SPM independent t -tests respectively. Results: A neutral, planovalgus and varus cluster were identified. Neutral feet showed mostly similar kinematics as typically -developing data. Planovalgus feet showed increased ankle valgus and Chopart dorsiflexion, eversion and abduction. Varus feet showed increased ankle varus and Chopart inversion and adduction. Significance: This study is the first to describe Chopart and Lisfranc joint kinematics in different foot deformities of children with CP. It shows that adding a midfoot segment can provide additional clinical and kinematic information. It highlights joint angles that are more distinctive between deformities, which could be helpful to optimize the use of multi -segment foot kinematics in the clinical decision making process.