Mechanical strength of scaphoid fixation.

We have investigated five devices suitable for scaphoid fixation (ASIF 2.7 mm and 3.5 mm cannulated screws, Herbert, Herbert-Whipple, and Howmedica Universal Compression Screw). The biomechanical properties tested were compression and resistance to cantilever bending. There was no statistically significant difference in compression between devices. There were significant differences in resistance to cantilever bending, with the Howmedica screw being strongest in both failure mode and in ultimate failure strength.