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Leg Alignment in Children

General practitioners are commonly consulted about concerns over leg alignment in toddlers. Salenius and Vankka (1975) described the normal development of the tibiofemoral angle in a child and plotted the curve to demonstrate this.

The typical development shows genu varum (bow legs) from birth up to approximately 20 months. After the age of two years the legs develop genu valgum (knock knees) with a peak occurring at three years of age. After this, the legs gradually assume the normal slightly valgus alignment of adults by approximately seven years of age.

There is the normal development of the lower limbs, and parents should be advised that the shape of the legs changes over time. There is a normal variation as to the timing of these changes and it is common for children to follow this curve for anything up to a year after the depicted timeline.

leg alignment

Growth development of tibio-femoral angle in children by Salenius and Vanka (1975)

Those with progressive deformity outside of the expected range or unilateral alignment changes should be monitored closely.

Causes of atypical genu varum (bow legs)

  • Blount’s disease (usually unilateral and progressive)
  • Trauma
  • Tumours
  • Infections
  • Rickets
  • Skeletal dysplas

Causes of atypical genu valgum (knock knees)

  • Trauma
  • Tumours
  • Infections
  • Rickets
  • Skeletal dysplasias

Risk factors for alignment abnormalities

  • Obesity
  • Vitamin D deficiency
  • Untreated flatfoot deformity with ligamentous laxity of knees