Objective To evaluate the effectiveness of percutanous fixation with helical bridge combined fixation system (BCFS) for treatment of long split fractures involving the middle and upper humerus. Methods Between February 2018 and February 2020, 15 patients of long split fractures involving the middle and upper humerus were treated. There were 6 males and 9 females, with an average age of 62 years (range, 37-82 years). The fractures were caused by slipping in 7 cases, falling from height in 3 cases, and traffic accident in 5 cases. According to AO classification, the shaft fractures were rated as type A in 4 cases, type B in 9 cases, and type C in 2 cases. And all fractures extended to proximal humerus; and the proximal fractures were rated as one-part fracture in 11 cases and two-part fracture in 4 cases according to Neer classification. The interval between injury and operation was 1-7 days (mean, 3.2 days). Nine patients underwent closed reduction and 6 patients underwent open reduction after lengthening the incisions. All fractures were percutaneously internal fixated with helical BCFS after reduction. The operation time, intraoperative blood loss, incision healing, and fracture healing were recorded. Constant-Murley score was used to evaluate shoulder joint function, and Mayo score was used to evaluate elbow joint function. ResultsThe operation time ranged from 55 to 175 minutes, with an average of 76.5 minutes; the intraoperative blood loss ranged from 80 to 300 mL, with an average of 185.5 mL. All incisions healed by first intention, without infection or radial nerve injury. All patients were followed up 12-23 months, with an average of 16 months. The fractures all reached clinical healing, and the healing time was 12-20 weeks, with an average of 14.5 weeks. At 1 year after operation, the Constant-Murley score of the affected side was 88.7±7.6, and there was no significant difference when compared with that of the healthy side (90.8±8.3) (t=1.421, P=0.052). According to the elbow Mayo score, the score of the affected side was 97.6±6.5, and there was no significant difference when compared with the healthy side (97.7±7.3) (t=0.433, P=0.913). ConclusionThe helical BCFS can avoid the dissection of deltoid insertion and prevent the iatrogenic radial nerve injury. With satisfied effectiveness, it is suggested for minimally invasive surgical treatment of long split fractures involving the middle and upper humerus.