Many foot, knee, and leg conditions that parents notice in their infants and young children eventually resolve without treatment. Some conditions initially exist because of the way the legs were positioned in the uterus before birth. Rarely, treatment is needed.

In flat feet (pes planus), the middle of the feet, which are normally arched, appear sunken. Before 3 years of age, all children have flat feet. The arch in the foot begins to develop around 3 years. Persistent flat feet may result when the arch of the foot is unusually flexible ( called flexible flat feet). Another cause of flat feet is stiffening of the foot joints, which fixes the foot in a position with a flattened arch (called tarsal coalition). Tarsal coalition may be a birth defect or result from conditions such as injuries or prolonged swelling.

Flexible flat feet usually cause no symptoms but sometimes cause pain or cramps in the feet. Tarsal coalition may cause pain or cramping. Feet with tarsal coalition are stiff, which can interfere with walking or running.

Flexible flat feet usually do not require treatment. However, if an older child has pains or cramps in the feet, corrective shoes may be needed. Treatment for tarsal coalition often includes a cast. Sometimes surgically separating the stiffened foot joint restores mobility to the foot.

In bowlegs (physiologic genu varum), the knees appear rotated away from each other. This appearance is due to the position of the hips and inward curve of the lower leg (tibial torsion) created by the position of the legs in the uterus before birth. Typically, this condition corrects itself within the first 2 years as the child begins to walk.

Abnormal growth of the tibia can lead to a condition called Blount disease (tibia vara), in which the legs are bowed significantly. Blount disease can affect one or both legs. Most commonly, it appears after the first year. However, it can develop in adolescence. Children younger than 3 years may be treated with leg braces. Older children may be treated with surgery.

In knock knees (genu valgum), the knees point inward. Knock knees most often affect children aged 3 to 5 years. Usually, the condition corrects itself by the age of 10 without treatment. If the condition persists into adolescence, surgery may be required.

Femoral torsion is curving of the thighbone (femur). In internal femoral torsion, the thighs curve inward. The knees and usually the toes point toward each other. in external femoral torsion, the thighs curve outward. The knees and toes point away from each other. Internal femoral torsion develops much more often than external femoral torsion. Children with internal femoral torsion sometimes have abnormally flexible joints and ligaments.

Internal and external femoral torsion usually resolve without treatment when the child is older and begins to walk. Sometimes internal femoral torsion is corrected by making sure that the child sits straight. Maintaining a straight sitting position may not be possible until the child reaches school age. Rarely, when internal femoral torsion persists past the age of 10, surgically straightening the bone may be necessary. It can take years for internal or external femoral torsion to resolve.