The Journal of Bone and Joint Surgery, Vol 75, Issue 11 1602-1609, Copyright © 1993 by Journal of Bone and Joint Surgery, Inc
Use of the metaphyseal-diaphyseal angle in the evaluation of bowed legs
MD Feldman and PL Schoenecker
Shriners Hospital for Crippled Children, St. Louis, Missouri 63131.
We evaluated the accuracy of the angle described by Levine and Drennan, the
metaphyseal-diaphyseal angle of the proximal aspect of the tibia, for the
differentiation of physiological bowing from Blount disease. We compared
this angle, as measured at presentation, in 106 children (179 extremities)
who had physiological bowing with the angle in nineteen children
(thirty-two extremities) who had documented Blount disease. The angle
averaged 9 +/- 3.9 degrees for the patients who had physiological bowing
and 19 +/- 5.7 degrees for the patients who had Blount disease (p <
0.0000001). Linear regression analysis, performed to evaluate any changes
in the metaphyseal-diaphyseal angle in relation to age, showed that the
older the child was at the time of presentation the more likely it was that
the angle would be smaller in a child who had physiological bowing and
larger in a child who had Blount disease. The chance for false-positive and
false-negative errors was greater than 5 per cent if the angle was more
than 9 degrees but less than 16 degrees. Sixty-six (37 percent) of the 179
extremities in the group that had physiological bowing had an angle of at
least 11 degrees; one extremity affected by Blount disease had an angle of
less than 11 degrees. In this study, we found that the
metaphyseal-diaphyseal angle may be helpful in the identification of Blount
disease but should not be the sole criterion used to determine the
diagnosis.
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