[Comparison of a radiation-independent aiming system and free-hand technique for distal locking of unslotted femoral nails].

Although the free-hand technique remains the most popular method for distal interlocking screw insertion, proximally mounted "radiation-independent" devices which compensate for implant deformation recently have been developed for rotationally stiff, unslotted femoral nails. However, the benefits of such systems have not been determined. This study prospectively compared the duration of the nailing procedure, the length of radiation time, and the accuracy of interlocking screw placement with a radiation-independent distal aiming system to those using the free-hand technique. In twenty paired intact cadaveric femora, a single surgeon experienced only in the free-hand technique performed statically locked intramedullary nailing using the two methods. For the aiming system and free-hand technique respectively, the total operation time was 19.1 +/- 8.4 versus 20.9 +/- 11.3 minutes (p = 0.9), the distal locking time was 6.6 +/- 2.4 versus 4.8 +/- 1.5 minutes (p = 0.002), the total fluoroscopy time was 23 +/- 17 versus 69 +/- 34 seconds (p < 0.0001), and the distal locking fluoroscopy time was 0 versus 37 +/- 15.5 seconds (p < 0.0001). There were no failures in either group. Drill nail contact (p < 0.0001) and distal screw damage (p = 0.02) were both greater with the free-hand technique.