From the Department of Mechanical Engineering, Biomechanics Division, Sharif University of Technology, Tehran, Islamic Republic of Iran
Abstract: (3564 Views)
This study compares the functional capabilities of different metacarpal
fixation constructs under physiological loadings in an attempt to identify the
optimal construct rather than the strongest one. One hundred and twenty-six
preserved human metacarpals were mechanically tested after oblique osteotomies
and internal fixation. Maximum load to failure, average structural rigidity, and
energy absorbed were determined. All the fixations, except the intramedullary
rods, tolerated the assigned physiological loadings below their failure limits in
tension and torsion. The safety factor for K-wire tension band in bendings was only
1.4, which is very low compared to those of dorsal plate fixation (4.3) and the two
interfragmentary lag screw fixation (4.0). Both torsional and axial rigidity of the
K-wire tension band fixation were significantly less than the two interfragmentary
lag screw fixation. Fixation by two interfragmentary lag screws was the optimal
method, providing adequate strength and stability while requiring less soft tissue
dissection than dorsal plate fixation.