Fig. 2From: Comparison of freehand technique and a novel laser-guiding navigation system in femoral neck-cannulated screw fixation: a randomized controlled trialWork principle sketch maps of the laser guiding navigation device (A). This meant that the horizontal plane X-ray central fluoroscopy axis of G arm (the green line), vertical plane X-ray central fluoroscopy axis (the red line) and the target screw passage central axis (the blue line) remain coaxial, known as “three-line coaxial” (B, C). The blue tube represented target channel (B)Back to article page