Tibial torsion is inward twisting of the tibia (shinbone) and is the most common cause of intoeing. It is usually seen at age 2 years. Males and females are affected equally, and about two thirds of patients are affected bilaterally.
Normally, lateral rotation of the tibia increases from approximately 5º at birth to approximately 15º at maturity; femoral anteversion decreases from approximately 40º at birth to approximately 15º at maturity.
In a study by Mullaji et al to determine tibial torsion norms, individuals in India were found to have less tibial torsion than Caucasians but about the same amount as the Japanese population.The differences in normal tibial torsion values are expected to be caused by the different lifestyles and postures of the different populations, such as cross-legged sitting positions.
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.
The natural history of femoral torsion 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.
Normal femoral anteversion is 40º in the newborn and decreases to 10º by the age of 8 years. The acetabulum is angled forward 15º. 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 can further correct by improving the gait through conscious effort until adolescence.
The patient’s history should consist of details of the age at onset, severity, disability, milestones, and family history.
- 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.
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. Imaging studies may be helpful. However, not every child who undergoes an evaluation because of torsional issues requires any or all imaging tests.
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.
Treatment with orthoses generally is ineffective. The condition has a benign natural history. Because most cases resolve spontaneously, observation with yearly review is all that is generally needed. True metatarsus adductus is an intrauterine positional deformity that resolves in 90% of cases by the age of 4 years. If no improvement is seen, cast correction by using a long leg cast can be attempted. A weekly cast change for 4-5 weeks is generally needed.
Osteotomy is indicated if deformity is more than 3 standard deviations (SDs) from the mean (less than -10º or more than +35º). Osteotomies (supramalleolar osteotomy) can be performed at any level.21,21
Osteotomy correction is indicated if the deformity is more than 3 SDs from the mean and is a cosmetic or functional problem (ie, internal rotation of 85º, external rotation of <10º).
Osteotomy can be performed at any level: subtrochanteric, shaft, or distal. Distal osteotomies are easier to fix and are associated with less blood loss and quicker healing.
The authors prefer supramalleolar osteotomies because they are easier to perform. Attention is directed toward making the bone cuts perpendicular to the long axis to avoid building an angular deformity into the rotational correction. A fibular osteotomy should be created to allow for stress-free tibial rotation. This also preserves the distal tibiofibular articulation. The osteotomy is made 2-3 cm proximal to the distal tibial physis.
Proximal tibial osteotomies must be performed distal to the tibial tuberosity to prevent rotation of the patellar tendon insertion that, if rotated externally, can predispose the patient to patellar maltracking in the trochlea and lateral patellar dislocation.
In younger children, osteotomies can be fixed by using Kirschner wires or small fragment plates. In older children, intramedullary devices, plates, or external fixation can be used. Ilizarov devices can be used with rotational boxes, but the Taylor spatial frame is best suited for rotational correction.
A size mismatch and some translation occur between the proximal and distal segments after significant rotational correction.
The metaphysis is the best place to perform an osteotomy in terms of the speed of healing. Proximal tibial metaphyseal derotation osteotomies alter the patellar tracking and the patellofemoral joint mechanics, and they are not preferred. Also, osteotomies can be performed in the distal tibia and fibula, which can be derotated as one functional piece, avoiding alteration of the ankle mechanics.
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