A lower limb difference is a leg that is missing, crooked, bowed, shortened, or a combination of these. There are many different reasons that could cause a lower limb difference.
Sometimes a child is born with a lower limb difference. This is called a congenital difference. Examples of congenital lower limb differences include:
Some lower limb deformities are associated with another condition. For example, children who are born with dwarfisms, such as achondroplasia, are often bowlegged.
A lower limb deformity can also be acquired, which means it develops over time. Some of the most common acquired lower limb deformities are caused by fractures or infections.
An underlying problem with the bone can also cause deformities. Children with rickets can have deformities because they have weak bones due to a lack of calcium and phosphate. Over time, the weak bones can bend. Similarly, lower limb deformities associated with multiple fractures can be caused by osteogenesis imperfecta (known as "brittle bone disease").
Limb deformities may be centered around certain joints, or can be due to various conditions.