Distal intramedullary nail interlocking: the flag and grid technique.

Distal interlocking in intramedullary nailing of long bone fractures accounts for a significant proportion of the total fluoroscopy and operative time. We describe a modification of the "perfect circles" freehand technique employing a metallic grid temporarily attached to the skin of the lateral surface of the femur or to the medial surface of the tibia that acts as a fixed "navigational" aid. The position of the distal nail holes in relation to the grid is fluoroscopically ascertained. Subsequently, under fluoroscopic control, a modified Steinmann pin with a metallic handle attached to its blunt end ("flag") is used to accomplish targeting and to create the screw holes, affording improved visualization. This technique was compared with the traditional freehand technique in 2 groups of patients. Use of the modified technique led to reduction of radiation exposure and total distal interlocking time, and there were no significant complications related to the technique.