A radiographic study of proximal radius anatomy with implications in radial head replacement

Anteroposterior (AP) and lateral radiographs of 20 healthy volunteers' forearms were taken in three views (full supination, neutral rotation, and full pronation). Radial head maximum diameter and angular measurements between the axis of forearm rotation (AFR) and the radial neck axis (RNA) were made with digital calipers. Repeated-measures analysis of variance revealed a statistically significant difference between the three AP groups, with supination having the smallest values (P <.0001), but not for the lateral groups (P =.128). Comparison of the AFR-RNA angle between the AP supinated position and the three lateral views revealed a statistically significant difference among all of the pairs, with the AP supinated position having the smallest values. The RNA most closely approximated the AFR with the forearm in the supinated position. For best approximating the native AFR during radial head replacement, the cut should be made perpendicular to the neck axis with the elbow extended and the forearm in the supinated position.