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.