O2111 A RADIOGRAPHIC STUDY OF PROXIMAL RADIUS ANATOMY, WITH IMPLICATIONS IN RADIAL HEAD REPLACEMENT

Abstract

Aims: The purpose of our study was to determine the radiographic anatomy of the proximal radius in three different views in order to identify that position, which has the smallest value for the angle between the axis of forearm rotation (AFR) and the radial neck axis (RNA). It is our hypothesis that such a position should offer the optimal situation for the radial neck cut in radial head replacement, as it will approximate the normal biomechanical axis of forearm rotation. Methods: Anteroposterior (AP) and lateral radiographs of 20 healthy volunteersñ forearms were taken in three views (full supination, neutral, full pronation). Radial head maximum diameter and angular measurements between the axis of forearm rotation (AFR) and the radial neck axis (RNA) were made utilizing digital calipers. Results: Repeated-measures analysis of variance (ANOVA) revealed a statistically signiþcant difference between the three AP groups, with supination having the smallest values (p< 0.0001), but not for the lateral groups (p=0.128). Comparison of the AFR-RNA angle between the AP supinated position and the three lateral views revealed a statistically signiþcant difference among all the pairs with the AP supinated position having the smallest values. Conclusions: The RNA most closely approximates the AFR with the forearm in the supinated position. To best approximate 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.