There are various causes of dwarfism, such as because of problems with skeletal development, such as cartilage malnutrition, or rickets with hypophosphatemia can result. Others are due to, for example, problems with pituitary gland function, leading to pituitary dwarfism, or mucopolysaccharide or Turner syndrome. The most common orthopedic-related dwarfism that requires orthopedic treatment is hypophosphatasia rickets, which is characterized by a relatively short height and a large curvature of the skeleton, resulting in obvious inversion of the knee and O-leg, and usually requires early surgical intervention, otherwise serious joint degeneration may occur at an older age. There are also patients with chondrodysplasia, which usually causes less severe O-leggedness, but the trunk length is close to normal, but the limbs are relatively short. Most people with chondrodysplasia or rickets generally have little effect on life expectancy.