Bow legs, medically known as genu varum, describe a condition where an individual’s legs curve outward at the knees, creating a noticeable space between the knees when the ankles and feet are together. This alignment is common in infants and toddlers.
Understanding Bow Legs
Bow legs can arise from various factors, including physiological and pathological causes. Physiological bowing is a normal developmental stage observed in many infants, often a result of their position in the womb. The bones rotate slightly to fit into the cramped space, leading to this outward curvature. This type of bowing typically resolves on its own as a child grows, usually by two to three years of age.
Pathological bowing stems from an underlying medical condition and may not correct without intervention. Rickets, a common pathological cause, results from a deficiency in vitamin D, calcium, or phosphorus, which are essential for healthy bone development. This deficiency softens and weakens bones, leading to bowing.
Another significant cause is Blount’s disease, or tibia vara, a growth disorder affecting the growth plates of the shin bone. This condition causes uneven growth, where the outer side of the tibia continues to grow while the inner side does not, leading to a pronounced outward bend. Other less common causes include certain types of dwarfism like achondroplasia, bone dysplasias, unhealed fractures, or exposure to toxins such as lead or fluoride.
Does Bow Legs Affect Height?
Most cases of physiological bow legs do not impact a person’s final adult height. This common type of bowing in infants and toddlers is a temporary alignment variation that resolves naturally as the child grows. Since it does not typically involve damage or disruption to the growth plates—the areas of cartilage at the ends of long bones responsible for longitudinal growth—it does not hinder the bones’ ability to reach their genetically determined length.
However, bow legs caused by underlying pathological conditions can affect a person’s stature. Conditions such as rickets can lead to permanent bone deformities and reduced height. Rickets impairs the proper mineralization of bone, disrupting the normal function of growth plates and preventing the long bones from lengthening effectively.
Blount’s disease, another pathological cause, directly involves an abnormality of the growth plate in the shin bone. In this condition, the inner part of the growth plate slows down or ceases growth, while the outer part continues to develop. This uneven growth can result in a significant limb length discrepancy between the affected leg and the other, potentially leading to a shorter overall height if the condition is severe or affects both legs and is not adequately managed. Any severe damage to a growth plate, whether from disease or injury, can impair its normal function, leading to uneven or stunted bone growth and ultimately affecting a person’s final height. Growth plates typically close near the end of puberty, around ages 13-15 for girls and 15-17 for boys, at which point longitudinal bone growth ceases.
When to Seek Medical Advice
While physiological bow legs often resolve naturally, certain signs warrant a medical evaluation to rule out underlying conditions. Seek medical attention if the bowing persists beyond two to three years of age, or if it appears to worsen over time. Also seek medical attention if the bowing is asymmetrical.
Other indicators for concern include the presence of pain in the knees, hips, or ankles. Limping, an awkward walking pattern, or difficulty with running can also suggest a more serious issue. If the child’s height is notably below the fifth percentile for their age, or if bowing begins in adolescence or adulthood, seek medical attention.
Diagnosis typically involves a thorough physical examination, observing the child’s gait and measuring the distance between the knees. X-rays may be ordered to visualize the bones and growth plates, helping identify conditions like rickets or Blount’s disease. Blood tests might also be conducted to check for nutritional deficiencies, such as vitamin D or calcium.