Orthofix external fixation of distal radius fractures: complications associated with screw size.

We did a retrospective analysis of 28 patients who were treated with the Orthofix external fixation system for complex fractures of the distal radius to study complications associated with screw size. The 14 patients in group 1 had a 4.5/3.5-mm tapered screw placed in the metacarpal bone; the 14 patients in group 2 had a 3.5/3.3-mm tapered screw placed in the metacarpal bone. Both groups had 4.5/3.5-mm tapered screws placed in the radius. Two patients in group 1 had metacarpal pin tract infections; no patients in group 2 had a distal pin tract infection. Two patients in group 1 had a fracture of the metacarpal; only one patient in group 2 had a fracture of the metacarpal. In both groups two patients had proximal pin tract infections at the radius screw fixation site. There was no screw breakage in either group. The unique design of the tapered Orthofix screw allows it to be removed almost painlessly in the clinic. At installation in the operating room, however, the surgeon must remember not to back the threaded pin out for fine adjustment of bony penetration. Any reverse excursion of the threaded shaft will loosen the tapered screw and cause early failure of the fixation. We no longer use the 4.5/3.5-mm screw when managing wrist fractures with the Orthofix external fixation system. It is now our policy to use the 3.5/3.3-mm screw for fixation of the Orthofix external frame to both the metacarpal bone and the radius.