Cubitus varus deformity after supracondylar fracture in children is caused by varus angulation and internal rotation of the distal fragment. An ultrasonographic measurement has been reported as a method of measuring the rotational deformity of the humerus. Yamamoto measured the rotation angle of the glenohumeral joint to clarify the rotational deformity of the distal fragment (Yamamoto's method). This paper presents a comparison of the ultrasonographic measurement and Yamamoto's method.
Twenty-five patients with supracondylar fractures were examined for rotational deformity of the humerus using both methods. They were followed for an average of 8 years (2-13 years). The ultrasonographically measured angle of the sound side subtracted from the affected side (HT') was on average 6.9±8.8°, and that of Yamamoto's method (IR') -1.4±16.9°.
If HT' and IR' both measured the rotational deformity of the distal fragment, then both angles should be the same. However, there was a distinct difference between them, as IR' was affected by limitation of internal rotation of the glenohumeral joint.
From this study, when we recommend that when evaluating rotational deformity of the distal fragment by Yamamoto's method, it is important to remember that IR' is affected by glenohumeral movement.
