Bow leg

Lateral bowing is not uncommon in infants and is normal in a child less than 2 years old. It can be caused by a growth disturbance of the tibial epiphysis and the tibial shaft.

• common from birth to the early toddler, often with out-toeing (maximal at approx. 1 year); most resolve by 18 months (1)

Consider and exclude rickets - particularly in individuals with a high phytate intake e.g. chapati eaters and vegetarians.

Measurement of the degree of deformity can be achieved by:

• getting the patient to stand with both patellae facing forward and then measuring the distance between them
• radiographic estimation: the angle between the longitudinal axes of both the femur and the tibia

Severe deformation may be amenable to osteotomy.

Notes:

• anterior bowing is always significant; causes include:
  • congenital absence of the fibula
  • neurofibromatosis type 1
  • osteogenesis imperfecta
• posterior bowing:
  • is rare
  • looks serious, but usually responds to simple stretching and splinting

Reference:

• ARC. Sports-Related Musculoskeletal Disorders. Reports on the Rheumatic Diseases 2008;14.