The application of distal aiming system in humeral intramedullary nailing

Objective To investigate the value of electromagnetic field real-time system (EFRTS) in the distal locking of intramedullary nailing for humeral shaft fractures. Methods From April 2015 to January 2017, data of 32 consequent patients with humeral shaft fracture (22 males, 10 females; ranged from 18 years to 78 years old, average of 40.4 years; 9 domestic falls, 15 traffic accidents, 6 fall from height, and 2 sports injury; AO12 A1: 9 cases; A2: 14 cases; A3: 4 cases; B2: 5 cases) were retrospectively analyzed. All were treated with Humeral Antegrade Locking Nail. For inserting the two distal locking screws, the SURESHOT Distal Targeting System was used. Results Accurate placement of the distal screws was accomplished in all 32 cases, which meant one drilling and one screw locking. The mean duration of the two distal screw locking was 197±30 s (range, 156-253 s) in the preparation phase and 393±39 s (range, 336-481 s) in the operation phase. The mean follow-up period was 18 months, ranging from 11 to 25 months. All the fractures were healed in an average time of 15.9 weeks, ranging from 12 to 20 weeks. The range of motion was: 80° to 180° in abduction (155° in average), 80° to 180° in anteflexion (160° in average), 60° to 100° in external rotation (80° in average), and 17 cases internal rotation to L3 level, 10 to T12 level and 5 to T7 level. The mean score of Constant-Murley was 89, ranging from 74 to 96. All the patients obtained good results. 27 patients restored self-care ability within 3 months after surgery. Shoulder discomfort occurred in 2 patients because of nail tail outside the articular surface. The symptom recovered after removal of the nail as well as joint release in arthroscopy. Conclusion The distal aiming device can be used in humeral intramedullary nailing, by which the distal screw can be inserted by one time. Meanwhile, it has the advantages of short time-consuming, secure operation, and no X-ray radiation. Key words: Humeral fractures; Fracture fixation, intramedullary; Bone screws; Surgery, computer-assisted