Coxa Valga Causes and Treatment

Coxa valga is increase in femoral neck shaft angle tp more than 140 degrees. Like coxa vara, coxa valga could be congenital or acquired.

But it is quite rare as compared to coxa vara.

Coxa valga is often associated with shallow acetabular angles and femoral head subluxation.

It can be associated with genu varum and lead to increased stress and early degenerative changes in the medial compartment of the knee.

Types of Coxa Valga

Commonest cause of progressive coxa valga is cerebral palsy along with other neuromuscular disorders. The increased muscular pull on the femoral head due to spasticity  and abnormal forces eventually may cause subluxation or dislocation. Coxa valga can be

True

this deformity may occur after arrest of the greater trochanter apophysis or neck cartilage following surgical procedures. It gives an appearnce of elongation of neck on AP radiographs.

Apparent

This appears due to femoral antetorsion which gives appearance of increased neck shaft angle.

Combinations

In neuromuscular disorders such as cerebral palsy, the deformity is usually a combination of femoral antetorsion and true coxa valga.

Changes in neck shaft angles after birth

Femoral neck shaft angle is also called also the caput-collum-diaphyseal (CCD) angle or the femoral angle of inclination.

Infants are born with approximately 150 degrees of coxa valga and this gradually drops to the adult normal of 115 to 120 degrees by age 8 years under the influence of the abductor force and walking. Most of this correction actually occurs by the time children are 2 to 3 years of age.

The direct cause of the coxa valga is the abnormal force on the proximal femoral growth plate.

The ability for remodeling the femoral neck shaft angle begins to diminish substantially in late childhood. By the adolescent growth spurt, the ability for the femoral neck shaft angle to remodel itself either into varus or recovering back into coxa valga is lost because there is not enough growth potential remaining for the growth plate to respond.

Causes of Coxa Valga

• Bilateral
  • Neuromuscular disorders, e.g. cerebral palsy
    • often have concurrent femoral anteversion
  • Skeletal dysplasias, e.g. Turner syndrome, mucopolysaccharidoses
• Unilateral
  • Trauma causing growth plate arrest

Imaging

Plain X-rays

The angle formed between the neck of the femur and its shaft is increased beyond >140 degrees

Femoral anteversion and rotation can affect measurement accuracy and should be considered when measuring angles.

Treatment

Coxa valga in a child is not necessarily a pathological condition which needs treatment as long as the acetabulum shows adequate development for the patients age and constitution. Varus osteotomy is not indicated in these cases and may even result in poor development of the hip following operation.

When required, it can be treated with corrective osteotomy.  Roatational coorection for anteversion if present should also be considered.

Varus derotation osteotomy  and angled blade-plate fixation is quite effective. The osteotomy is done at an intertrochanteric or subtrochanteric osteotomy is performed.