Treatment protocol
bleeding, fractures, femoral neck fracture, fracture-healing
BLEEDING
All the patients were placed in the supine position on a special traction table using the G-arm machine. In the freehand group, the distal guide pin was first placed under the perspective of the G-arm machine; the other two guide pins were then placed with using the parallel drill guide. After accurate positioning, the screw channels were enlarged using a hollow drill along the guide pin, and three parallel cannulated screws (WASTON, Cannulated Compression Screws, diameter 7.3 mm) of suitable length were inserted for fixation. In the laser group, the positioning ring and laser emitter were calibrated before the operation; the patient was then anesthetized and disinfected, and the distal guide pin was inserted under laser-line guidance. The other two guide wires were also placed using the parallel drill guide. After the position was confirmed using fluoroscopy, three parallel cannulated screws were inserted in the same manner as in the freehand group (Fig. 

The operation time, radiation-exposure time, first success rate, amount of bleeding, visual analog scale (VAS) score, Harris score, and fracture-healing time were recorded and used for comparison among the two groups. All the patients were monitored at 1, 2, 3, 6, and 9 months postoperatively, or the follow-up ended after fractures healed (Fig. 
Preoperative X-ray and three-dimensional CT image of 39 years male with femoral neck fracture (