Biomechanical evaluation of fixation of intra-articular fractures of the distal part of the radius in cadavera: Kirschner wires compared with calcium-phosphate bone cement

Background: The purpose of this study was to compare the biomechanical effi cacy of an injectable calcium-phosphate bone cement (Skeletal Repair System [SRS]) with that of Kirschner wires for the fixation of intra-articular fr actures of the distal part of the radius, Methods: Colles fractures (AO pattern, C2.1) were produced in ten pairs of fresh-frozen human cadaveric radii. One radius from each pair was randomly chosen for stabilization,vith SRS bone cement. These ten radii were treated with open incision, impaction of loose cancellous bone with use of a Freer elevator, and placement of the SRS bone cement by injection. In the ten co ntrol specimens, the fracture was stabilized with use of two horizontal and two oblique Kirschner wires. The specimens were cyclically loaded to a pea k load of 200 newtons for 2000 cycles to evaluate the amount of settling, o r radial shortening, under conditions simulating postoperative loading with the limb in a cast. Each specimen then was loaded to failure to determine its ultimate strength. Results: The amount of radial shortening was highly variable among the spec imens, but it was consistently higher in the Kirschner-wire constructs than in the bone fixed with SRS bone cement within each pair of radii. The rang e of shortening for all twenty specimens was 0.18 to 4.51 millimeters. The average amount of shortening in the SRS constructs was 50 percent of that i n the Kirschner-wire constructs (0.51 +/- 0.34 compared with 1.01 +/- 1.23 millimeters; p = 0.015). With the numbers available, no significant differe nce in ultimate strength was detected between the two fixation groups. Conclusions: This study showed that fixation of an intra-articular fracture of the distal part of a cadaveric radius with biocompatible calcium-phosph ate bone cement produced results that were biomechanically comparable with those produced by fixation with Kirschner wires. However; the constructs th at were fixed with calcium-phosphate bone cement demonstrated less shorteni ng under simulated cyclic load-bearing. Clinical Relevance: A calcium-phosphate bone cement with high compressive s trength may provide adequate stability of the fracture and therefore serve as an alternative to Kirschner wires with their associated complications.