A BIOMECHANICAL COMPARISON OF 4 METHODS OF FIXATION OF THE TRAPEZIOMETACARPAL JOINT

Four methods of internal fixation for trapeziometacarpal arthrodesis w ere evaluated for biomechanical stability under axial compression, tor sion, and cantilever bending in either flexion-extension or radial-uln ar deviation. The techniques tested included crossed Kirschner wires, cerclage wiring, cup and cone with a single oblique Kirschner wire, an d a tension band technique that has not Previously been reported. Resu lts reported included stiffness (load/deformation) of the construct an d toggle (displacement without load applied, after cyclic loading). Th e tension band and cerclage techniques provided greater construct stif fnesses in axial loading than crossed Kirschner wire or cup-and-cone f ixation, and toggle was significantly lower than for specimens Fixed b y the cup-and-cone technique. In torsion the tension band technique pr oduced fixation that was significantly stiffer than cup-and-cone fixat ion. in cantilever bending the differences between fixation systems we re not significant, except between cerclage and cup-and-cone technique s 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 loadi ng.