There are several different types of knee differences, including:
Congenital knee deformities are something a child is born with. The three most common congenital limb deficiencies of the lower limb (congenital femoral deficiency, tibia hemimelia, and fibula hemimelia) often involve the knee joint. In addition to these limb deficiencies, many genetic musculoskeletal disorders involve congenital knee deformities (such as achondroplasia, Morquio's syndrome, etc.) In rare cases, a child may be born with a dislocated knee that is stuck in a straight position. Normally, a baby is born with his or her knees in a bent position and the knees straighten gradually over time.
Developmental deformities form because of an abnormality in childhood development. For example, children who are born bowlegged can go on to become knock-kneed once the bowlegged condition resolves. Knock knees is a condition where the knees point inward and touch. In most cases, knock knees resolve by age 6. However, if the crookedness does not resolve on its own and continues to worsen, treatment may be needed to correct the deformity.
Acquired deformities are typically caused by a fracture or infection. Sometimes, when a child breaks his or her bone in the growth plate, it may cause only part of the bone to grow, even if the fracture heals. This “partial growth arrest" can lead to a limb being both short and crooked. Infections may also affect a bone’s growth plate. If your child has recently had a fracture or infection involving the growth plate, your doctor will follow the growth of your child’s limb for at least 6 to 12 months to determine if there are any problems.