Radiographic Evaluation of the Distal Radioulnar Joint: Technique to Detect Sigmoid Notch Intra-Articular Screw Breach in Distal Radius Fractures

Appropriately Matched Fixed-Angle Locking Plates Improve Stability in Volar Distal Radius Fixation

Purpose

Size options for volar locking plates may provide value for distal radius fixation. We compared excessively narrow plates with plates that were appropriately matched in width for fixation of an multifragmented distal radius fracture model.

Methods

Eighteen matched pairs (right and left wrists) of large, cadaveric male distal radii specimens, prepared with a simulated Arbeitsgemeinschaft für Osteosynthesefragen type C-3 distal radius fractures, were tested. One specimen from each matched pair was randomized to receive a plate that was appropriately matched in width to the distal radius. The contralateral limb received a narrow plate, which in all cases was undersized in width. Fixation stability was tested and compared to the contralateral matched specimen. Specimens were preloaded at 50 N for 30 seconds before cyclic loading from 50–250 N at 1 Hz for 5000 cycles then loaded to failure.

Results

Loss of fixation under cyclic loading was significantly greater in the specimens fixed with excessively narrow plates compared with plates of appropriate width. When loaded to failure, the plates of appropriate width were stiffer, with higher force at failure and compressive strength than narrow plates. The primary mode of failure was displacement of the distal lunate facet fragment.

Conclusions

These findings suggest that optimally matching the volar locking plate width to the radius may provide advantages for stability of the fixation construct and fragment capture. This may be due to reduced stress concentration from the distribution of forces across a larger surface area.

Clinical relevance

Optimizing the plate width to the radial width may improve fracture stability and may carry additional importance in comminuted fractures, where narrow plates may not completely capture small bone fragments.

Radiography of the Distal Radius

Imaging of the distal radius is of paramount importance in diagnosing injuries, indicating patients for operative or nonoperative treatment, and appropriately following patients for associated injuries and complications. Plain radiographs and fluoroscopy are the dominant imaging modalities in all settings because they are readily available and provide valuable information about the osseous structures and any instrumentation. Computed tomography can offer more information about implant placement and the level of comminution of the articular surfaces but is more expensive and exposes patients to higher doses of radiation. Magnetic resonance imaging is less commonly used but is useful for occult fractures and other associated injuries. Ultrasonography is gaining popularity in evaluating implant placement, especially regarding tendon impingement and subsequent tendon injury.