Supplemental pinning improves the stability of external fixation in distalradius fractures during simulated finger and forearm motion

External fixation is commonly used in the treatment of distal radius fractu res. In this in vitro study, we investigated changes in fracture stability when using supplemental radial styloid pinning in combination with external fixation. Eight previously frozen cadaveric upper extremities were mounted in a computer-controlled wrist-loading apparatus. This device was used to generate finger and forearm motions through loading relevant tendons. An un stable extra-articular distal radius fracture was simulated by removing a d orsal wedge from the distal radius melaphysis. An electromagnetic tracking system measured fragment motion following randomized application of a Hoffm an external fixator, a Hoffman external fixator with 2 supplemental radial styloid pins, and a dorsal 3.5-mm AO plate. Regardless of the fixation tech nique used in this unstable fracture model, fragment motion occurred when p ostoperative finger and forearm motions were simulated. The addition of rad ial styloid pins to a construct stabilized by an external fixator significa ntly improved fragment stability, approaching that achieved with the dorsal AO plate. (J Hand Surg 1999;24A:992-1000. Copyright (C) 1999 by the Americ an Society for Surgery of the Hand.)