Genu Varum, commonly known as “bull legged” or bowleggedness, is an orthopedic condition characterized by an outward bowing of the legs. This alignment issue causes a noticeable gap between the knees when a person stands with their ankles together. While often a temporary and normal part of development in infants, persistent or worsening bowing indicates a medical concern requiring evaluation.
What Exactly is Genu Varum
Genu Varum is a lower limb deformity where the tibia and femur meet at an angle that causes the knee to point outward from the body’s midline, resulting in the characteristic bowed appearance. This is most visible when the feet are placed together and the knees remain separated. The condition is typically measured by assessing the distance between the medial femoral condyles, known as the intercondylar distance.
The majority of infants and toddlers exhibit physiological bowing, which is considered normal development. This is often a remnant of the cramped fetal position and is expected to resolve spontaneously as the child grows. Physiological bowing usually peaks between six and 24 months of age and naturally corrects itself by the time the child reaches two to three years old.
Pathological Genu Varum, in contrast, does not self-correct and may worsen over time. This form of bowing is caused by an underlying disease or structural abnormality that affects bone growth. If left unaddressed, pathological bowing can lead to functional issues like an awkward gait, pain, and a higher risk of developing knee osteoarthritis in adulthood due to uneven joint loading.
Common Causes and Underlying Factors
Pathological bowing stems from disorders that disrupt the normal growth and mineralization of the bone structure. A well-known cause is Rickets, a condition resulting from a deficiency in Vitamin D, calcium, or phosphate. Inadequate intake of these nutrients impairs bone calcification, causing the bones to soften and bow under the stress of walking.
Another cause is Blount’s disease (tibia vara), an abnormality of the growth plate in the upper shinbone (tibia). This disorder causes abnormal growth on the inner side of the knee joint, leading to a progressive inward angle of the tibia. Blount’s disease is often seen in children who are overweight or begin walking at a very early age.
Skeletal dysplasias, which are genetic disorders affecting bone development, can also cause Genu Varum. Trauma or infection to the growth plates during childhood can similarly result in asymmetric bone growth, leading to progressive bowing on one side. These factors require specific diagnosis and management to prevent severe deformity.
Diagnosis and When to Seek Medical Attention
The diagnostic process begins with a physical examination to assess leg alignment and rule out normal physiological bowing. A physician will measure the intercondylar distance to quantify the degree of bowing. Serial measurements are often taken over time to determine if the condition is resolving or progressing.
X-rays are typically used to differentiate between physiological and pathological causes. These images allow the physician to evaluate bone structure and the condition of the growth plates, looking for specific signs of Rickets or Blount’s disease. Blood tests may also be ordered to check for nutritional deficiencies or metabolic disorders, such as low Vitamin D levels.
Parents should seek medical attention if:
- The bowing is asymmetrical (only one leg is affected).
- The deformity is progressive and noticeably worsening.
- There is a lack of spontaneous improvement by age two, or if bowing persists beyond three to four years of age.
- There is pain, a limp, or an intercondylar separation greater than six centimeters.
Management and Treatment Options
Treatment for Genu Varum is determined by the underlying cause, the child’s age, and the severity of the deformity. For physiological bowing, the primary approach is observation, as the condition spontaneously corrects itself with normal growth. No special braces or orthotic devices are needed.
Non-Surgical Management
If the bowing is pathological, addressing the underlying cause is the first step, such as providing nutritional supplementation for Rickets. Bracing or orthotics may be used in the early stages of Blount’s disease in young children to help guide the growth of the shinbone. Bracing is generally not effective for other forms of pathological bowing.
Surgical Correction
For progressive or severe cases in children who are still growing, a minimally invasive surgical technique called guided growth is often preferred. This procedure involves placing a small metal plate (like an eight-plate) on the outer side of the bone near the growth plate. The plate acts as a tension band, slowing growth on the bowed side while the unaffected side continues to grow, gradually straightening the limb.
In older adolescents or adults whose bones have finished growing, or for very severe deformities, a corrective osteotomy may be required. This surgery entails cutting the bone, realigning it to the correct angle, and fixing it in place with hardware. The goal of all treatments is to restore the mechanical axis of the leg, preventing long-term joint complications and improving overall function.