Causes / typical injury mechanism: During the seventh week of gestation, the lower limb internally rotates while the hip and femur externally rotate, reflecting the newborn posture. Abnormalities result due to extrinsic constraints that are secondary to in utero crowding, which can be due to factors resulting from the mother, fetus, or a combination of both.

Classic history and presentation: Typically, a child or adolescent presents with concern with cosmesis, abnormal gait, tripping, falling, issues wearing shoes, or lower limb pain, especially in the patellofemoral region. It is often unilateral and more commonly the right side.

Prevalence:

• Age – Typically presents in patients between 4 and 7 years and worsens during late childhood and adolescence.
• Sex / gender – equal incidence between sexes

Risk factors:

• Preterm infancy
• Familial history
• Malunion of tibial fractures
• Neuromuscular conditions (eg, polio, myelodysplasia)

Pathophysiology: The tibia externally normally rotates 15 to 20 degrees while the femur externally rotates 25 degrees during normal childhood development, which can worsen the condition as the child grows older.