Causes of Knock-knees: Generally, the lack of balanced diet, especially vitamin D, calcium and phosphorus is the main cause of knock-knees. It may also be caused due to rickets. Chronic illness, obesity, flatfoot and carrying heavy weight in early age may be other possible causes of Knock-knees.
Causes of Bow legs: The main cause of bow legs is the deficiency of calcium and phosphorus in bones. Long bones of legs become soft, hence they are bent outward. The chances of bow legs also increase when children become overweight. This deformity may be due to the deficiency of vitamin D. Improper way of walking and forcing the babies to walk at a very early age may also lead to Bow legs.