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.

 

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

 

Recommendations

• Address obesity
• Check vitamin D and treat as per Vitamin D Policy
• Medial arch supports for those with genu valgum where this increases deformity at knees
• Referral for children with increasing genu varum past four years
• Referral for children with increasing genu valgum past eight years
• To allow the possibility of guided growth do not delay referral past 10 years of age