use this- Clubfoot is a deformity in which an infant's foot is turned inward, often so severely that the bottom of the foot faces sideways or even upward. Approximately one infant in every 1,000 live births will have clubfoot, making it one of the more common congenital (present at birth) foot deformities.
So if the size of the pore is small then the rate of the diffusion will be very slow as the molecules will move from high concentration to low concentration in very slow rate.
