Precontoured Fixed-Angle Volar Distal Radius Plates: A Comparison of Anatomic Fit

Purpose To compare distal radius volar fixed-angle plates for anatomic fit. Methods Twenty embalmed radii were stripped of soft tissues. The volar lip (watershed line) on the volar distal radius served as a reference line. Seven volar fixed-angle plates were tested (Acumed Acu-loc Standard, Hand Innovations DVRAW and DVRAN, Synthes Juxta-articular [JA], Synthes Extra-articular [EA], Trimed Volar Bearing, Zimmer Volar Lateral Column). Four parameters of anatomic fit were studied: (1) site of best fit; (2) percent plate contact; (3) pin–subchondral bone distance; and (4) extraosseous penetrations. The Wilcoxon signed rank test and Pearson's correlation coefficient were used to compare interobserver plate placement. A Kruskal-Wallis analysis of variance was used to compare percent plate contact and pin–subchondral bone distance across all plates. The Bonferroni correction for multiple comparisons was used to compare pin–subchondral bone distances for all possible plate combinations. Results There was no difference between observers for plate placement. Each plate had a specific site of best fit, and the 7 plates varied widely in best fit location. Percent contact (range, 3% to 6%) between plates was significantly different. Pin–subchondral bone distance across all plates was significantly different. Analysis of all possible plate combinations showed that the Synthes EA pin–subchondral bone distances were significantly different than those of all plates except Zimmer. Amongst the 140 plate insertions, the radiocarpal joint was penetrated in 17, the styloid in 7, (with 6 associated with the DVRAW plate), and the distal radioulnar joint in 9 (all associated with the DVRAW plate). Conclusions There was considerable variation in ideal plate location among the 7 plates tested. Total contact was minimal for all plates tested. The Synthes EA pin–subchondral bone distance was significantly greater than those of other plates tested. Joint penetration was relatively common, necessitating use of fluoroscopy and proper plate width.