Objective:To evaluate the clinical efficacy of modified anterior subacromial approach plate internal fixation for three- or four-part valgus impacted proximal humeral fractures.Methods:A retrospective analysis of 35 patients treated between November 2018 and November 2021 at Fuzhou Second General Hospital was performed, including 15 males and 20 females aged 61.7±7.8 years (range: 40 to 73 years). Patients were classified under the Neer system; 17 had 3-part fractures and 18 had 4-part fractures. The modified approach accessed the fracture site via the natural interval of the deltoid anterior bundle, facilitating fracture reduction and fixation using a plate. Operative time, incision length, intraoperative fluoroscopy time, follow-up duration, Constant-Murley score, fracture healing time, visual analogue scale (VAS) for pain, and humeral neck-shaft angle were assessed. Intraoperative and postoperative complications were also recorded.Results:All patients underwent successful surgery, with an average incision length of 8.1±0.3 cm (range, 7.6-9.0 cm) and intraoperative fluoroscopy time of 6.6±0.3 seconds (3-part fractures: 6.3±0.2 s, 4-part fractures: 6.8±0.2 s, t=6.350, P<0.001). Follow-up averaged 22.1±5.8 months (range, 14-31 months). Fracture healing occurred in 11.8±1.4 weeks (range, 10-15 weeks). At the final assessment, the VAS score was 1.6±0.7 (range, 1-3), the Constant-Murley score was 89.6±2.9 (range, 84-95), and the humeral neck-shaft angle was 133.4°±3.1° (range, 128°-138°; 3-part fractures: 133.6°±3.5°, 4-part fractures: 133.3°±2.8°, t=0.288, P=0.075). No complications such as avascular necrosis of the humeral head, varus collapse of the fracture site, or axillary nerve injury were recorded. Conclusion:The modified anterior subacromial approach plate internal fixation is a minimally invasive, safe, and effective treatment for valgus impacted three- and four-part proximal humeral fractures, demonstrated by excellent surgical outcomes and absence of major complications.