A biomechanical comparison of four methods of fixation of the trapeziometacarpal joint

Four methods of internal fixation for trapeziometacarpal arthrodesis were evaluated for biomechanical stability under axial compression, torsion, and cantilever bending in either flexion-extension or radial-ulnar deviation. The techniques tested included crossed Kirschner wires, cerclage wiring, cup and cone with a single oblique Kirschner wire, and a tension band technique that has not previously been reported. Results reported included stiffness (load/deformation) of the construct and toggle (displacement without load applied, after cyclic loading). The tension band and cerclage techniques provided greater construct stiffnesses in axial loading than crossed Kirschner wire or cup-and-cone fixation, and toggle was significantly lower than for specimens fixed by the cup-and-cone technique. In torsion the tension band technique produced fixation that was significantly stiffer than cup-and-cone fixation. In cantilever bending the differences between fixation systems were not significant, except between cerclage and cup-and-cone techniques in flexion-extension. On the basis of our results in a biomechanical model, the tension band technique offers superior fixation in torsion, the cerclage technique in flexion-extension, and both in axial loading.