Fig 4. The mean values of the sagittal plane prosthetic ankle angles (left, +ve dorsiflexion) and prosthetic ankle moments (right, +ve plantarflexor) of subject (ID: TF4) during stance phase in level ground normal speed walking compared with the mean non-amputee group data.

The sagittal plane ankle movement in the Esprit foot is simulated by the deformation of the foot’s heel and forefoot keels.