Even more common than deformities around the hips are deformities around the knee. These differences can be due to a multitude of different reasons, including but not limited to the following:
Congenital knee deformities are something a child is born with. In rare circumstances, a child may be born with a dislocated knee in which the knee is stuck in a straight position. Normally, a baby is born with her knees in a bent position and then they straighten gradually over time. The three most common limb deficiencies of the lower limb (congenital femoral deficiency, tibia hemimelia, and fibula hemimelia) often include the knee joint as part of the congenital problem. In addition to these limb deficiencies, many genetic musculoskeletal disorders, involve congenital knee abnormalities (such as achondroplasia, Morquio's syndrome, etc)
Developmental deformities imply that there is an abnormality to the typical childhood development. Children are often born "bow-legged". This typically improves by the age of 2 to 2 1/2. Afterwards, a child typically becomes knock-kneed, and this will resolve by around the age of 6. In some cases, the crookedness does not resolve on its own, and if it continues to worsen or fails to improve, some type of treatment may be necessary to help correct the deformity.
Acquired deformities occur typically due to some type of fracture or infection. Sometimes, when a child breaks his bone in the growth area, there are times that only part of the bone grows, but not the whole bone. Even if the fracture heals. "This partial growth arrest" can lead to both the problem of a limb being both short and crooked. Infections may also involve a growth area, with a similar problem occuring as what is described for fractures. If your child has or has recently had a fracture or infection involving the growth area, your doctor will guide you through the process and follow the growth of your childs' limb for at least 6-12 months to determine if there are any growth problems.