A pathological bowing of the leg (genu varum). Unlike the physiological bowlegs of the infant and toddler, the bowing in Blount’s disease progressively worsens after the first 2 years of life and is often unilateral. The condition is more common in girls than in boys and more common in blacks than in European Americans. Most cases occur in the first 2 or 3 years of life, but a juvenile form (onset at age 4 to 10 years) and an adolescent form (onset at 11 years or older) are recognized.