Badly fitting shoes are bad for kids' feet.
The Austrian Research Project on "Children's Feet-Children's Shoes" proved for the first time that shoes which are too short can have negative effects on children's feet (download publication biomed_artikel.pdf)
When children only rarely wear too-small shoes, there are no serious consequences to worry about (aside from reddened skin, blisters and painful feet). It gets worse when children's shoes are always too small, during different stages of development. Also, children's feet need "Shoe free time".
The toe joints
Wearing shoes which are too short and tight distorts the natural position of the toes. The results: painful joints and changes in the position of the toe joints (e.g. Hallux Valgus, bunions).
When the toes are cramped in the shoes, it changes the natural direction of the toe muscles. The results: muscle and tendon pain, inflammation and a dystrophy, or shortening, of the foot muscles.
Shoes which are too short force the foot into an unnatural position, which can cause circulatory problems. The results: sensations of cold and numbness, vein problems (e.g. varicose veins).
The whole organism
A weak foundation influences the whole body. The change in posture caused by foot injuries can result in knee, hip and back problems. Even the heart and circulatory system can be indirectly affected: Fact is, many athletic activities require healthy feet (for example jogging). Unhealthy feet can therefore lead to a reduction in physical activity, which is known to be the root of a number of disease-causing factors (lack of fitness, high blood pressure, etc.).