To compare the mechanical stability of an intramedullary (IM) screw with two crossed interfragmentary compression screws for fixation of the 1st MTPJ in ten pairs of cadaveric feet. One foot underwent fixation with two crossed 4.0-mm cannulated cancellous screws. The contralateral foot was fixed with an IM 1.6-mm Kirschner wire and an IM 6.5-mm partially threaded cancellous lag screw. A plantar-to-dorsal load was applied to the distal end of the proximal phalanx at a rate of 1 mm/sec. Failure was defined as gross actuator displacement of 5 mm. Stiffness was defined as the slope of the force versus deformation curve between 10 and 60 N. Strength was defined as the load at failure. The differences in stiffness and strength parameters between the two fixation techniques were checked for significance (P <
0.05) with a paired t-test.
The intramedullary MTP joint fixation was significantly stiffer (18.7 ± 10.1 N/mm) than control group fixation (10.2 ± 6.1 N/mm). Similarly MTP joint fixation in the IM group was stronger (149.2 ± 88.2 N) than that of the control group (100.2 ± 70.8 N), but this was not significant (P = 0.07).
The IM technique resulted in a stronger stiffer fixation when compared with the standard crossed lag screw technique.
