Metaphyseal-diaphyseal angle in Blount's disease. A 30-year follow-up of 13 unoperated children.

We analyzed the metaphyseal-diaphyseal angle in 13 patients with infantile Blount's disease, who had been followed without treatment during the entire growth period and without any form of realignment procedure in adulthood. On diagnosis at 23 (17-35) months of age, the metaphyseal-diaphyseal angle varied between 7 degrees and 25 degrees. At follow-up, most of the legs were almost straight. We found that the diagnosis of Blount's disease cannot be based solely on the metaphyseal-diaphyseal angle and that a bowed knee must be followed with repeated examinations before it can be decided whether treatment is needed.