In-toeing (pigeon toe) is a condition in which the foot turns inward more than expected during walking or running relative to the line of progression. Out-toeing (slew foot) occurs when the foot turns outward more than expected during walking or running relative to the line of progression.

Toeing-in and toeing-out are frequently seen at all ages and are caused by a variety of conditions affecting the feet, ankles, legs, knees, and hips. In-toeing is more common than out-toeing and is more likely to be caused by benign conditions. Protective or compensatory shifting of the body weight to the middle or outside of the foot in pronation and knock-knee, both normal developmental stages, is the most common cause of toeing-in and corrects itself in time. Developmental bowing of the legs, also self-correcting, may lead to temporary toeing-in. Talipes equinovarus and metatarsus varus are associated with toeing-in. Spasticity of the internal rotator muscles of the hip, as seen in cerebral palsy, produces toeing-in, as does anterior maldirection of the acetabulum.

Toeing-out is seen with calcaneovalgus and pes planovalgus. Flaccid paralysis of the internal rotator muscles of the hip results in toeing-out. Posterior maldirection of the acetabulum produces toeing-out.

The remaining causes of both conditions are related to internal or external torsion of the tibia and femur. In general, with toeing-in, if the child's patellae are noted to be rotated inward (kissing knees) while walking, then the underlying problem is above the knee; if they face straight forward, then the underlying problem is below the knee.[12]

Parents often notice excessive inward or outward toeing-in infants or toddlers. Excessive in-toeing is more common than out-toeing and is more likely to be caused by benign conditions that usually represent variations of normal development from excessive rotations of the femur, the tibia, or both. In children, in-toeing does not usually cause pain or interfere with development or stability of gait. Therefore understanding the natural progression of femoral and tibial torsion, as well as the changes that occur in hip rotation, is essential for primary care physicians to reassure and advise parents about these common conditions.

Finding older family members with histories of these rotational anomalies is not uncommon. In many instances, a history of a parent who was treated as a toddler with an orthotic device for these conditions can even be found.

Inward rotation of the femur at the femoral neck (femoral anteversion) is greatest at birth (approximately 40 degrees) and gradually declines to adult values of 10 to 15 degrees by age 8 years.

The best position in which to assess the rotation of the lower extremities is with the child in the prone position, the hips fully extended, and the knees flexed to 90 degrees. To measure hip rotation, the lower leg is used as a pointer and the legs are rotated through the axis of the hip joint (Figure 183-14 and Figure 183-15). Until 1 or 2 years of age, the clinical measurement of hip rotation is limited by the physiological tightness of the hip joint capsule, therefore underestimating the degree of femoral anteversion. After the age of 18 to 24 months, measurement of hip rotation is a close approximation of bony femoral rotation, averaging 50 degrees of internal rotation and 40 degrees of external rotation.

The easiest way to assess tibial rotation is to measure the thigh-foot angle, the axis of the foot relative to the axis of the thigh (see Figure 183-16 and Figure 183-17). The normal thigh-foot angle ranges from 0 to 30 degrees of external rotation; therefore an internal thigh-foot angle indicates internal tibial torsion. By age 2 years, children typically walk with the foot turned out relative to the line of progression. A thigh-foot angle of 10 to 15 degrees is normal in adults and older children.

Figure 183-14 Starting position for measuring hip rotation with the hip extended while the child is in the prone position. (Reprinted with permission from Joint Motion Method of Measuring and Recording. Rosemont, IL, American Academy of Orthopedic Surgeons, 1965.)

Figure 183-15 Internal rotation. (Reprinted with permission from Joint Motion Method of Measuring and Recording. Rosemont, IL, American Academy of Orthopedic Surgeons, 1965.)

In-toeing and out-toeing rarely require imaging studies. Evaluation using gait analysis may help in differentiating the cause of the abnormality for individuals with extreme in-toeing or out-toeing.

Families must be reassured about the natural history of rotational variations in the femur and tibia. Most children will simply outgrow their variant. An orthopedic or neurologic evaluation should be made if a child has severe in-toeing or an unsteady gait (especially while running), causing stumbling as the toes catch on the back of the trailing leg. A referral may also be advised if a child's condition does not follow the expected physiologic progression with growth.[13] [14]