Baumann's confusing legacy.

Abstract

Dr Ernst Baumann has been credited with describing an angle that can be measured from radiographs taken of children's elbows. This article presents three variations in the definition of this angle that we found in the orthopaedic literature. Variation I is the angle between the long axis of the humerus and a line through the physis of the lateral condyle of the distal humerus. Variation II is the angle between the perpendicular to the long axis of the humerus and a line through the physis of the lateral condyle. Variation III is the angle between the line through the physis of the lateral condyle and a line connecting a point on the edge of the trochlea to a point at the lateral limit of the physis of the lateral condyle. By reading translations of two of Baumann's own articles, we have realised that he used variation I when assessing the radiographs. He did, however, believe that the reciprocal angle, variation II equalled the carrying angle of the elbow and this can be demonstrated by Fig. 1, which has been taken from an article that was published in 1929. The relationship between this angle and the carrying angle has since been proven to be more complex than Baumann believed. We recommend that a descriptive term such as the 'shaft-physeal' angle would cause less confusion and variation in the definition of this angle.