Distal locking of femoral nails: evaluation of a new radiation-independent targeting system.

OBJECTIVES The purpose of this study was to assess the effectiveness of a novel radiation-independent aiming device for distal locking of intramedullary nails in a human cadaver model. METHODS A new targeting system was used in 25 intact human cadaver femora for the distal locking procedure after insertion of an intramedullary nail. The number of successful screw placements and the time needed for this locking procedure were recorded. The accuracy of the aiming process was evaluated by computed tomography. RESULTS The duration of the distal locking process was 8.0 ± 1.8 minutes (mean ± SD; range, 4-11 minutes). None of the screw placements required fluoroscopic guidance. Computed tomography revealed high accuracy of the locking process. The incidence angle (α) of the locking screws through the distal locking holes of the nail was 86.8° ± 5.0° (mean ± SD; range, 80°-96°). Targeting failed in 1 static locking screw because of a material defect in the drilling sleeve. CONCLUSIONS This cadaver study indicated that an aiming arm-based targeting device is highly reliable and accurate. The promising results suggest that it will help to decrease radiation exposure compared with the traditional "free-hand technique."