Biomechanical Evaluation of Various Screw Constructs for Proximal Phalanx Base Fracture Fixation

To evaluate the biomechanical properties of four fixation methods for proximal phalanx base fractures, single antegrade cannulated screw (control), V-pattern, Y-pattern, and K-wire configurations, using a matched pair cadaveric model.

Forty-eight fingers (index through little) from six matched cadaveric hand pairs were included. A standardized transverse base fracture was created in the proximal phalanx. One side of each pair received a single antegrade cannulated screw. Contralateral digits were treated with either a V-pattern (group 1), Y-pattern (group 2), or K-wire configuration (group 3). Specimens underwent 3-point bending, rotational testing, and cantilever bending to failure using a hydraulic test frame. Key metrics included bending stiffness, torsional stiffness, axial displacement, and peak load to failure.

The V-pattern demonstrated considerably higher bending stiffness, reduced displacement, greater rotational stiffness, and higher torque resistance compared to controls. While failure displacement was similar, the V-pattern required considerably higher force to fail and showed greater stiffness. The Y-pattern showed no notable differences in bending stiffness or displacement versus controls. However, it had considerably lower rotational stiffness and torque resistance. No differences in failure load, stiffness, or displacement were noted. The K-wire showed considerably lower bending stiffness and higher displacement compared to controls. Rotational metrics and failure parameters showed no notable differences.

Among the configurations tested, the V-pattern demonstrated superior biomechanical stability across bending, torsional, and failure testing compared to single antegrade cannulated screw and dual K-wire supporting our hypothesis. These findings support further investigation into its clinical application for improved fixation in proximal phalanx base fractures. Moreover, the addition of a smaller screw to make the Y-pattern did not add considerable strength.

Diagnostic IV.