Genu varum, commonly known as bow-leggedness, describes an outward curvature of the legs where the knees remain far apart when the ankles are touching. The need for intervention varies significantly depending on the underlying cause and the person’s age. A professional diagnosis is necessary to determine if the bowing is a normal part of development or a condition that requires medical attention. Treatment strategies range from simple observation to complex surgical procedures aimed at restoring the mechanical alignment of the lower limb.
Understanding Genu Varum
Genu varum represents an angular deformity in the coronal plane, meaning the mechanical axis of the leg deviates toward the midline. This condition is categorized into two main types: physiological and pathological bowing, a distinction that determines the treatment approach. The appearance of bow legs is often exaggerated by walking and can sometimes be associated with a waddling gait in children.
Physiological Bowing
Physiological bowing is considered a normal variation of development, commonly seen in infants and toddlers under two years of age. The bowing typically peaks between six and twelve months, a natural stage of lower limb development. This type is symmetrical, painless, and is expected to spontaneously resolve as the child grows. The legs usually straighten completely, reaching a normal adult configuration by about three to four years of age without medical intervention.
Pathological Bowing
Pathological bowing is defined as a persistent or progressive curvature that does not resolve by the expected age of three or four years. The mechanical axis of the limb falls into the inner quadrant of the knee, placing abnormal loading on the medial side of the joint. This continuous stress can lead to long-term consequences, including knee pain, joint instability, and an increased risk of developing early-onset osteoarthritis if left uncorrected.
Primary Causes and Diagnostic Requirements
Pathological bowing occurs due to a variety of underlying conditions that affect bone growth and structure. The most common cause is Blount’s disease, or tibia vara, which involves an abnormality of the growth plate in the upper part of the shinbone, or tibia. In Blount’s disease, the inner side of the growth plate slows or stops growing while the outer side continues, causing a progressive bowing effect.
Another frequent cause is Rickets, a bone disease resulting from a prolonged deficiency of Vitamin D, calcium, or phosphorus, which are necessary for healthy bone mineralization. Rickets causes the bones to become weak and soft, leading to characteristic bowing under the stress of weight-bearing. Other causes include skeletal dysplasias, previous trauma, infection, or a poorly healed fracture that resulted in asymmetrical growth.
Diagnosis begins with a physical examination to assess leg alignment and measure the intercondylar distance (the space between the knees when the ankles are touching). To confirm the diagnosis and determine severity, a physician will order standing, full-length X-rays of the lower limbs. These X-rays are crucial for measuring the mechanical axis deviation and identifying specific radiographic features, such as those found in Rickets or Blount’s disease. Blood tests may also be performed to check for underlying metabolic or nutritional issues, particularly Vitamin D deficiency, when Rickets is suspected.
Non-Surgical Management Strategies
For children with confirmed physiological bowing, the primary management strategy is simple monitoring and observation. Regular check-ups allow the physician to ensure the bowing is spontaneously resolving as expected and to compare the degree of varus to normal growth curves. Intervention is often unnecessary unless the bowing persists beyond the age of three or four.
In cases of nutritional Rickets, the underlying cause is addressed through medical management involving dietary changes and supplementation. Increasing the intake of Vitamin D and calcium is usually the first line of treatment, often leading to correction of the bone weakness over weeks to months. Treating the metabolic disorder is paramount, as it removes the factor driving the bone deformity.
Bracing or orthotics are sometimes employed for growing children with early-stage Blount’s disease or unresolved pathological bowing. Devices like a modified knee-ankle-foot orthosis (KAFO) are used to apply corrective pressure to the bone as the child grows. This non-invasive method works by guiding the developing bone into a straighter position, but compliance is demanding, often requiring the brace to be worn both day and night.
Physical therapy and specific exercises, such as those targeting hip and core stability, cannot change a structural bone deformity but can be complementary to medical treatment. Exercises may help strengthen surrounding muscles, improve overall stability, and manage symptoms like pain or balance issues. Isolated exercise is not a “fix” for the underlying skeletal misalignment and cannot replace necessary medical or surgical correction for significant bowing. For adults with mild cases, orthotic shoe inserts may be recommended to improve foot mechanics and reduce strain on the knee joint.
Corrective Surgical Interventions
When non-surgical methods fail or when the bowing is severe, progressive, or diagnosed after the growth plates have closed, surgery becomes the definitive corrective option. For children whose growth plates are still open, a procedure called guided growth, or hemiepiphysiodesis, is often used. This minimally invasive technique involves placing a small metal plate, often figure-eight shaped and about the size of a paperclip, on one side of the bone near the growth plate.
The plate temporarily restricts growth on the outer, faster-growing side of the limb, allowing the inner, slower-growing side to catch up and gradually straighten the leg. Since the bone is not cut, recovery is quick, and the child can typically bear weight immediately after the procedure. The plate is removed once the desired correction is achieved, a process that usually takes about twelve months, depending on the child’s growth rate and the degree of initial curvature.
For adolescents whose growth plates are nearly closed, or for adults, the standard surgical correction is an osteotomy. This is a more involved procedure where the surgeon cuts the affected bone (typically the tibia or sometimes the femur) to realign it. The bone is then repositioned to restore the mechanical axis of the limb to a normal alignment. The realigned bone is secured using internal fixation, such as plates and screws, or an external fixator to allow the bone to heal in the corrected position. The principal goal of this surgical approach is to restore the normal weight-bearing axis of the limb, which helps prevent future joint deterioration.