Fig. 2From: Comparison of freehand technique and a novel laser guiding navigation in distal locking of femoral intramedullary nails: a randomized controlled trialWork principle sketch maps of the device. This meant that the X-ray central fluoroscopy axis (the yellow line), the two laser lights cross axis (the red line) and the target screw passage (the blue line) remain coaxial, known as “three-line coaxial”. The blue tube represented a nail holeBack to article page