What is it?

Blount's disease is a condition of disturbed growth of the medial (inner) growth plate of the upper tibia, causing severe bowing of the leg at the knee. In 60% of cases, the condition affects both legs. Most frequently, it affects children before the age of 3 years, and is called the infantile form. No one knows the cause of the disease, although it is considered a developmental disturbance that affects just that portion of the growth plate at the knee. It affects predominantly children of African descent.

If untreated, the medial portion of the growth plate at the upper tibia stops producing bone, causing asymmetrical growth at the knee and progressive bowlegs. The deformity can get quite severe, and leads to early severe degenerative arthritis of the knee.

What does your doctor do about it?

Below the age of 3, Blount's disease can be difficult to distinguish from physiological bowlegs. X-rays can be done to look for changes characteristic of Blount's disease, or by measuring of the metaphyseo-diaphyseal angle (MTD angle). A MTD angle of 11 degrees or more is suspicious, and bears close observation. In established cases, a knee-ankle-foot orthosis (KAFO) to protect the knee is used, although its effectiveness is not proven. In the more severe cases, surgery to correct the deformity is indicated. It usually consists of an osteotomy (cutting the bone) just below the knee, and use of an external fixation device to hold the correction.