Objective:To compare the clinical effects between proximal humerus internal locking system (PHILOS) inverted and a posterior single plate in the anterior percutaneous minimally invasive internal fixation for distal humeral shaft fractures.Methods:A retrospective study was conducted to analyze the data of 65 patients with distal humeral shaft fracture who had been treated from January 2018 to May 2021 at Department of Orthopaedics, The Second Hospital of Fuzhou. The patients were assigned into 2 groups according to different treatment methods. In the observation group of 30 cases subjected to anterior percutaneous minimally invasive internal fixation with PHILOS inverted: 20 males and 10 females with an age of (41.5±11.6) years; type A in 5 cases, type B in 14 cases, and type C in 11 cases by AO fracture classification. In the control group of 35 cases subjected to anterior percutaneous minimally invasive internal fixation with a posterior single plate: 23 males and 12 females with an age of (39.9±11.2) years; type A in 7 cases, type B in 17 cases, and type C in 11 cases by AO fracture classification. The preoperative general data, operation time, intraoperative blood loss, total incision length, fracture healing time, and shoulder and elbow VAS scores, Constant-Murley shoulder function score, Mayo elbow performance score (MEPS), and complications at the last follow-up were recorded and compared between the 2 groups.Results:There was no significant difference in the preoperative general data between the 2 groups, showing comparability ( P>0.05). There were no significant differences either in operation time, fracture healing time, or shoulder or elbow VAS pain score, Constant-Murley shoulder function score, or MEPS at the last follow-up between the 2 groups ( P>0.05). The intraoperative blood loss was (59.7±26.6) mL in the observation group and (165.7±86.4) mL in the control group, and the total incision length was (10.7±2.1) cm in the observation group and (18.6±2.7) cm in the control group, showing statistically significant differences between the 2 groups ( P<0.01). There was no injury to the radial nerve or musculocutaneous nerves, incision infection or fracture nonunion in the observation group. There were 4 cases of iatrogenic radial nerve injury, 2 cases of incision infection and 1 case of fracture nonunion in the control group, yielding a complication rate of 20.0% (7/35). The difference in the incidence of complications was significant between the 2 groups ( P<0.01). Conclusion:In the treatment of distal humeral shaft fracture with anterior percutaneous minimally invasive internal fixation, PHILOS inverted has advantages of less soft tissue damage, less intraoperative bleeding, and a lower risk of iatrogenic radial nerve injury than the posterior single plate.