Excerpt from Tibial Torsion

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Normal development

Femoral anteversion decreases from approximately 40° at birth to approximately 15° at maturity. Lateral rotation of the tibia increases from approximately 5° at birth to approximately 15° at maturity.

Problem

Tibial torsion

Medial torsion improves with time. Lateral torsion often worsens because the natural progression is toward increasing external torsion. The ability to compensate for tibial torsion depends on the amount of inversion and eversion present in the foot and on the amount of rotation possible at the hip. Internal torsion causes the foot to adduct, and the patient tries to compensate by everting the foot and/or by externally rotating at the hip. Similarly, persons with external tibial torsion invert at the foot and internally rotate at the hip.

Femoral torsion

The natural history of this condition is to resolve by the time the patient is aged 8-9 years. Beyond this age, all remodeling will have occurred, and any further correction is due to a conscious modification of posture.

Femoral anteversion

Normal femoral anteversion is 40° in the newborn and decreases to 10-15° by the age of 8 years. The acetabulum is angled forward 15°. Femoral anteversion does not increase the risk of arthritis of the hip. Spontaneous improvement in the anatomic position can occur until the patient is aged 8 years and by improving the gait through conscious effort until adolescence.

Clinical

The patient's history should consist of details of the age at onset, severity, disability, milestones, and family history.

Clinical scenarios

• In children younger than 18 months, metatarsus adductus is the most common condition that causes intoeing.
• Between the ages of 18 months and 3 years, tibial torsion is the most common condition.
• In children older than 3 years, femoral torsion is the most common diagnosis.

Examination

The diagnosis is based on clinical findings, and other investigations generally are not required. Examination must include tests to exclude hip dysplasia, hip and ankle ranges of motion, and knee varus or valgus, which can cause apparent errors in examination. In some cases, imaging studies may be helpful (see Imaging Studies). However, not every child who undergoes an evaluation because of torsional issues requires any or all of these imaging tests.

Evaluation

Parents are generally more concerned about intoeing than the children are. Severe intoeing can cause the child to trip or run awkwardly, and it can interfere with their participation in sports. Excessive wear is seen along the lateral border of the shoe, mainly in the front half, because the child uses this as the presenting border of the foot on the heel- or foot-strike.

A rotational profile consists of the following:

• Foot progression angle (FPA)
• Tibial version or torsion
  • Thigh foot axis (TFA)
  • Transmalleolar angle
• Femoral anteversion (hip rotation)
• Shape of the foot

The FPA is the angular difference between the axis of the foot and the line of progression. Normal FPA is 10-15° of external rotation. By convention, external rotation values are positive, and internal rotation values are negative. Degrees of intoeing are as follows:

• Mild is -5 to -10°.
• Moderate is -10 to -15°.
• Severe is more than -15°.

Tibial version or torsion is the degree of rotation of the tibia along its long axis from the knee to the ankle. It is measured with the patient prone with his or her knees flexed to 90°. It is assessed by using the following 2 measures:

• Thigh foot axis: This is measured with the patient prone and the knees flexed to 90°, with the examiner looking at the feet from above. It is the angle between the line of axis of the thigh and the line along axis of foot. A normal TFA is 10-15° of external rotation. By convention, external rotation values are positive, and internal rotation values are negative.
• The transmalleolar axis is the axis of the line joining the 2 malleoli. Because the lateral malleolus is normally posterior to the medial malleolus, the transmalleolar axis is externally rotated by 15-20°, as measured with reference to the coronal plane axis. A transmalleolar axis rotated externally greater than 20° signifies external tibial torsion, and a transmalleolar axis rotated externally less than 10° signifies internal tibial torsion.

Femoral anteversion is the axial angle between the plane of the neck of the femur and the femoral condyles. It can be clinically deduced by measuring the hip rotation. Normal range of external rotation is 45-70°, and internal rotation is 10-45°. As femoral anteversion increases, the amount of internal rotation increases and external rotation decreases. These children can have as much as 90° of internal rotation and 0° of external rotation. They sit in the W position with their legs turned out (a position not attainable by normal adults), but they cannot sit cross-legged.

The shape of the foot is best assessed with the patient standing and examined from the back, or the patient is prone and the feet are assessed by looking at the soles of the feet. Metatarsus adductus (or uncommonly, abductus) can be seen.

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