Well because the human body was designed to be symmetrical, If this were to happen the child would live until the body compensates, with an uneven gait. This uneven gait can affect the curvature of the spine if it goes on long enough causing exaggerated curvatures, called Scoliosis.
Here is an interesting fact though, a fracture through the epiphyseal plate of developing children when broken can actually stop growth of the bone causing almost the exact same thing.
These will help him to decide what kinds of food are healthier, and eating more fruits and vegetables help provide the body with necessary vitamins and minerals that will keep your body healthy and reduce risk of disease
