Patrick Riegner, Christian Spiegel, F. Peter Kohler, Heike Kielstein, Ivan Zderic, Boyko Gueorguiev-Rüegg, Mark Lenz, Wolfram Weschenfelder
In this unstable intra-articular fracture model with radiodorsal metaphyseal comminution, six distal screws reduced post-cyclic axial deformation and radial fragment-shaft micromotion compared with four screws. The clinical relevance of these findings remains to be determined.
INTRODUCTION: This biomechanical study compared the fracture stability of a palmar plate combined with a headless compression screw (HCS) with that of a radiopalmar double-plate construct for AO/OTA 23-C2.1 distal radius fractures with metaphyseal defect zones. MATERIALS AND METHODS: Eleven matched pairs of cryopreserved human radii were prepared with standardized AO/OTA 23-C2.1 fractures. Left radii (n = 11) were fixed with a palmar plate plus HCS, while right radii (n = 11) received a radiopalmar double-plate construct. Construct stiffness and axial displacement were assessed using a universal testing machine. Interfragmentary range of motion (ROM) and rotation (ROT) were quantified using an optical three-dimensional motion-tracking system. Measurements were obtained before and after 5000 cycles of dynamic axial loading at 150 N. Two specimen pairs were excluded due to early failure or incomplete data acquisition. RESULTS: Both constructs demonstrated comparable stiffness and axial displacement, with no implant loosening or hardware failure observed. Interfragmentary ROM did not differ significantly between groups. However, the plate–HCS construct showed greater variability in rotational parameters. Initial radial-shaft rotation was significantly greater in the plate–HCS group (1.14° vs. 0.51°, p = 0.02). After cyclic loading, ulnar-shaft rotation increased significantly in the plate–HCS group (0.97° to 1.16°, p = 0.02) but not in the double-plate group. CONCLUSION: In this cadaveric model, fixation with a palmar plate combined with an HCS provided comparable axial stability but demonstrated greater variability and less consistent rotational control compared with radiopalmar double plating. Clinical studies are required to determine whether this less invasive construct achieves equivalent outcomes in vivo.