Blount's disease is a growth disorder of the tibia that causes the lower leg to angle inward, resembling a bowleg.It is also known as "tibia vara". It is named after Walter Putnam Blount, an American pediatric orthopedic surgeon. It has also been known as Mau-Nilsonne Syndrome, after C. Mau and H. Nilsonne, who published early case reports of the condition.
Symptoms and signs
Bowing of one or both legs that may:
Be rapidly progressive
Appear asymmetric
Primarily occur just below the knee
Complications
Failure to treat Blount's disease may lead to progressive deformity. Blount's disease may come back after surgery, especially in younger children. Because of the bowing, a leg-length discrepancy may result. This may result in disability if the discrepancy is significant and is not treated.
Causes
Blount's disease occurs in young children and adolescents. The cause is unknown but is thought to be due to the effects of weight on the growth plate. The inner part of the tibia, just below the knee, fails to develop normally, causing angulation of the bone. Unlike bowlegs, which tend to straighten as the child develops, Blount's disease is progressive and the condition worsens. It can cause severe bowing of the legs and can affect one or both legs. This condition is more common among children of African ancestry. It is also associated with obesity, short stature, and early walking.
Diagnosis
shows the lower legs to be angled inward. An x-ray of the knee and the lower leg confirms the diagnosis.
Differential Diagnosis
Lower extremity deformities in Rickets can closely mimic those produced by Blount's disease. To differentiate between Rickets and Blount's disease it is important to correlate the clinical picture with laboratory findings such as calcium, phosphorus and alkaline phosphatase. Besides the X-ray appearance. Bone deformities in Rickets have a reasonable likelihood to correct over time, while this is not the case with Blount's disease. Nevertheless both disorders may need surgical intervention in the form of bone osteotomy or more commonly guided growth surgery. Osteochondrodysplasias or genetic bone diseases can cause lower extremity deformities similar to Blount's disease. The clinical appearance and the characteristic radiographic are important to confirm the diagnosis.
Treatment
Children who develop severe bowing before the age of 3 may be treated with knee ankle foot orthoses. However, bracing may fail, or bowing may not be detected until the child is older. In some cases, surgery may be performed. Surgery may involve cutting the shin bone to realign it, and sometimes lengthen it as well.Other times, the growth of just the outer half of the tibia can be surgically restricted to allow the child’s natural growth to reverse the bowing process. This second, much smaller surgery is most effective in children with less severe bowing and significant growth remaining. Return to normal function and cosmetic appearance is expected if the knee can be properly aligned.
