Knee Angular Deformities (Knock legs and Bow legs)
Angular deformities of the knee are common during childhood and usually are variations in the normal growth pattern. Angular deformity of the knee is a part of normal growth and development during early childhood. Physiologic angular deformities vary with age as:
- During first year: Lateral bowing of tibia
- During second year: Bow legs (knees and tibia)
- Between 3-4 years: Knock Knees
The condition usually becomes more evident when the child is 2 to 3 years old and normally corrects itself by the time a child is 7 or 8 years old. However, if the condition is not corrected it could be a sign of an underlying disease that requires treatment.
A perfectly aligned knee has its load-bearing axis on a line that runs through the hip, knee and ankle. Based on the inward/ outward inclination of the head of tibia/fibula; knee angular deformities are classified as:
- Genu valgum (knock-kneed): Head of tibia/fibula (not the joint itself), is inclined away from the midline of the body
- Genu varum (bow-legged): Head of tibia/ fibula is inclined toward the midline of the body
Genu Varum (bowed legs): Bowed legs are very common in toddlers. If a child has bowlegs, one or both legs curve outwards. When your child stands there is a distinct space between the lower legs and knees. Bowed legs are rarely seen in adolescents. In most of the cases, children with bowed legs are significantly overweight.
The common causes of bowed legs include:
- Physiologic Genu Varum: Most children below the age of 2, show bowing of the legs as a part of normal physiological process. Normally the bowing will correct by 3 to 4 years of age and the legs may have a normal appearance.
- Blount's disease: It is a condition in which there is an abnormality of the growth plate at the upper portion of the tibia (shinbone).
- Rickets: It is bone disease that occurs in children due to deficiency of calcium, phosphorus, or vitamin D that are essential for healthy bone growth.
The most obvious symptom is bowing of the legs that appear when a child stands and walks. Other common symptoms are awkward walking pattern and turning in of the feet (intoeing). Bowed legs usually does not cause any pain, however discomfort in the hips, knees, and/ or ankles may occur during adolescence.
Genu valgum (knock-kneed)
Knock knees is a condition in which the legs curve inward at the knees. When a child stands, the knees appear to bend toward each other and the ankles are spread apart.
Knock knees most often develop as a part of normal growth. In some cases, especially if the child is 6 years of age or older, knock-knees may occur as a result of other medical problems such as injury of the shin bone, osteomyelitis (bone infection), overweight, and rickets.
The diagnosis of bow legs or knock knees is made through a physical examination. In addition, X-rays may be taken if a child is older than 2 ½ years and has symmetrical legs.
Treatment for Bow legs
As the child grows the condition usually corrects itself. For children with severe, unresolved bow legs, doctors may recommend non-surgical treatment options such as bracing, physical therapy, and medications. If non-surgical treatment options do not correct your child's bow legs, then surgery is considered.
Treatment for Knock-knees
Most children with knock knees do not require any treatment, but if the condition persists after age 7, then a night brace attached to an orthopaedic shoe may be recommended. If the separation between the ankles is severe, surgery may be an option.