Femur loading during gait in newly walking children

Femoral loading conditions are key in biomechanical analysis and prediction of fracture risk in children. Biomechanical assessment may be particularly useful in children with bone fragility disorders who may have greater risk of fracture during early developmental stages of mobility. However, a complete characterization of femoral loading during this early stage of walking has not been previously reported. Our primary goal was to develop regression models to characterize femoral loading at the hip during gait in newly walking children. Gait and kinetic analyses were conducted for children aged 13-23 months to obtain hip joint loading during walking experiments. 3D hip joint reaction forces and moments were determined. Regression models were developed to predict peak hip loading using subject characteristics and walking speed as factors. 16 gait cycles from 5 subjects were analyzed. Mean peak resultant hip force was 1.19 N/BW (0.22 SD, normalized by body weight, BW) and the corresponding mean peak resultant hip moment was 0.24 Nm/(BWxL) (0.08 SD, normalized by BW, and leg length, L). Predictive models for resultant hip force and hip moment based on age, height, and walking speed yielded R² values of 0.97 and 0.94, respectively. Hip joint loading in newly walking children was experimentally determined and predictive models of peak hip loading in gait were described for these children. Regression models predicting subject-specific peak hip joint loading can be applied in future applications such as subject-specific fracture risk assessments using finite element analysis without having to conduct gait experiments.