Central screw placement in percutaneous screw scaphoid fixation: a cadaveric comparison of proximal and distal techniques.

PURPOSE

Percutaneous screw fixation of acute minimally displaced scaphoid fractures is an attractive treatment alternative compared with cast immobilization and can be performed with either a distal/volar or proximal/dorsal approach. Central screw placement within the scaphoid appears to be an important factor for successful fixation. The purpose of this cadaveric study is to investigate whether the proximal or distal approach for percutaneous screw scaphoid fixation allows for more central placement of the screw.

METHODS

Twelve fresh frozen cadaveric upper limbs were studied, with 6 specimens assigned to scaphoid screw placement with a proximal approach and 6 matched specimens assigned to scaphoid screw placement with a distal approach. After screw placement, the scaphoid was sectioned evenly into quarters along the longitudinal proximal-distal axis. For each section, the distance from the center of the screw hole to the edges of the dorsal/volar/radial/ulnar axes was measured, and the means of the 2 groups were compared with a Hotelling's T(2) test to determine statistically significant central screw placement.

RESULTS

A statistically significant difference was found between the mean location of the distal fixation group and the center of the scaphoid in the midwaist and distal pole of the scaphoid (p =.007 and.012, respectively) and between the mean location of the proximal and distal fixation groups in the distal pole of the scaphoid (p =.045).

CONCLUSIONS

We find that the proximal/dorsal approach to the percutaneous screw fixation of scaphoid waist fractures allows for a more central placement in the distal pole, but there is no significant difference when it is used in the proximal or waist region. It remains unclear whether the more central screw placement afforded by the proximal approach might translate into an improved clinical outcome.