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

External fixation is commonly used in the treatment of distal radius fractures. 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 unstable extra-articular distal radius fracture was simulated by removing a dorsal wedge from the distal radius metaphysis. An electromagnetic tracking system measured fragment motion following randomized application of a Hoffman external fixator, a Hoffman external fixator with 2 supplemental radial styloid pins, and a dorsal 3.5-mm AO plate. Regardless of the fixation technique used in this unstable fracture model, fragment motion occurred when postoperative finger and forearm motions were simulated. The addition of radial styloid pins to a construct stabilized by an external fixator significantly improved fragment stability, approaching that achieved with the dorsal AO plate.