Leg alignment refers to whether the legs are straight or not
Normal development of the legs involves the following changes;
Bow leg (varus) in the infant which aligns to straight legs by 18 months and then into a knock knee (valgus) around 3-4 years and then straight legs (adult alignment) by around 7 years.
These changes are mild and should not cause limp or discomfort.
The figure below demonstrates the normal changes of alignment at different ages
More information about bow legs, knock knees are available.
Indications for concern and referral are available.
The photograph below shows severe knock knee abnormality - this is asymmetrical and extreme and therefore not a normal variant.