Non-union of the scaphoid. Treatment with cannulated screws compared with treatment with Herbert screws.

We retrospectively reviewed the results for thirty-four patients in whom a non-union of the scaphoid had been treated with bone-grafting and internal fixation with use of one of two types of screws as well as the temporary placement of Kirschner wires parallel to the screw to prevent rotation. The patients were divided into two groups: Group 1 contained sixteen patients who had been managed with a Herbert screw from 1986 through 1989 and Group 2, eighteen patients who had been managed with a 3.5-millimeter cannulated AO/ASIF screw from 1990 through 1992. There were no clinical or radiographic differences between the two groups. The time to union, confirmed with tomography, was 7.6 +/- 3.6 months for Group 1 and 3.6 +/- 1.2 months for Group 2. This difference was significant (p < 0.01). Both screws significantly improved the alignment of the scaphoid and decreased carpal collapse (p < 0.05). Regardless of the type of screw used, the time to union was significantly shorter when the screw had been placed in the central one-third of the scaphoid (p < 0.05). Seventeen of the eighteen cannulated screws had been placed centrally, compared with seven of the sixteen Herbert screws (p < 0.01).