Genu Varum, or bowleg, is defined as an outward bowing of the knee in relation to the thigh. This results in one or both of the knees being more lateral than the hips and ankles. A parent may first notice this abnormal posturing at birth or when the child begins walking. This can be a scary time for most parents.
It is important to first note that the most common cause of bowleg is idiopathic physiologic genu varum. While this long and confusing name may sound scary, it simply means that the cause is due to normal genetic variations and nothing more serious. Many children grow out of this type of genu varum by the age of 2 without treatment. In cases where the genu varum angles worsen over time or persist after the age of 2, treatment options include bracing, orthoses, or surgical correction.
When a child presents with severe genu varum presentation, genu varum worsening over time, or genu varum persisting past 4 years of age, more serious causes of genu varum must be ruled out. Below is a brief description of several of these causes of genu varum.
Causes of Genu Varum (Bowleg):
- Blount’s Disease: This disease is manifested by failure of inner part of tibia (shin bone) to develop, resulting in progressive deformity without treatment. Diagnosis is made through physical exam and x-rays.
- Rickets: Rickets is caused by insufficient vitamin D, leading to softened bones. Posture and gait abnormalities may be most pronounced following growth spurts or during winter months, when sunlight is low. Diagnosis is made through physical exam, x-rays, and blood work.
- Osteochondroma: Benign bone tumor found usually near the growth plates of long bones. Mass grows with skeletal growth. Increased pressure and mass on lateral part of knee result in appearance of genu varum. Diagnosis is made through physical exam, x-rays, and biopsy.
- Osteogensis Imperfecta: Abnormal Collagen, in amount or quality, result in easily fractured bones and shorted stature. Genu varum results from repeated trauma to inner part of tibia restricting growth. Diagnosis is made through x-ray and genetic testing.
- Pathologic Anterolateral Bow of the Tibia: Results from failure of tibia and fibula to unite. This places the limb at a greater risk for fracture during the first year of life. Diagnosis is made through x-ray.
 Leach, J. (2006). Orthopedic Conditions. In Campbell, SK, Vander Linden DW, and Palisano RJ (Eds.), Physical Therapy for Children (481-515). St. Louis: Saunders Elsevier.