Anatomical Fit of the Volar Locking Plate for Distal Radius and Influence of the Plate Size.

Purpose: The volar locking plates (VLPs) for distal radius fractures are currently available in different shapes and size options. Therefore, we investigated whether the anatomical fit and plate size of VLPs affect their proper placement. Materials and Methods: Two sizes of Acu-Loc2 Proximal Plates (AcuLoc), three sizes of Variable Angle LCP Two-Column Volar Distal Radius Plate 2.4 (VALCP), and 16 formalin-fixed cadaver specimens were studied. Computed tomography scans were performed on both the plates and forearms. The plate was fixed to a radius, and radiographs were obtained using fluoroscopy. X-rays were superimposed, and a three-dimensional image of the plate and bone was created. The distance from the plate to the bone (PBD) was measured, and the contact area between the bone and plate was analyzed. We measured the distance between the distal end of the plate and the watershed line, defining it as watershed overlap. Results: The PBD in the radial column was significantly smaller than that in the ulnar column in the narrow and standard VALCP, as well as in the narrow AcuLoc. For the other plates, it tended to be smaller in the radial column than in the ulnar column. The contact area on the plate was small, and the average value of the watershed overlap was negative for both plates. However, no significant differences in each measurement item were observed among the plate sizes. Conclusion: Although the small plate size affected the fitting to the distal radius, the variance was minimal; therefore, each plate size may be selected depending on the circumstances of the fracture. Level of Evidence: Diagnostic Level III.