Objective:To compare the clinical efficacy of interlocking intramedullary nail (IMN) versus minimally invasive percutaneous plate osteosynthesis (MIPO) combined with locking plate internal fixation in the treatment of elderly humeral surgical neck fractures. Methods:A retrospective analysis was conducted on 102 patients with humeral surgical neck fractures admitted between October 2023 and October 2025. Based on the internal fixation method, patients were divided into an IMN group (n=51) and a MIPO plate group (n=51). Perioperative parameters, healing time, Neer shoulder scores at 3 and 12 months postoperatively, and complication rates were recorded and compared between the two groups. Concurrently, biomechanical testing was performed using artificial humeral models to verify differences in fixation stiffness between the two techniques. Results:Compared with the MIPO locking plate group, the IMN group demonstrated shorter operative time and less intraoperative blood loss (P<0.05). No significant differences were found in incision length or hospital stay between the two groups (P>0.05). The fracture healing time was significantly shorter in the IMN group than in the MIPO group (P<0.05). At 3 months postoperatively, the IMN group had a significantly higher excellent/good rate of Neer score compared with the MIPO group (P<0.05), whereas at 12 months, the difference was not statistically significant (P>0.05); however, the MIPO group showed superior shoulder range?of?motion scores (P<0.05). Biomechanical testing revealed that the IMN group had superior axial compressive stiffness and failure load compared with the locking plate group (P<0.05). No significant difference was observed in complication rates between the two groups (P>0.05). Conclusion:Both minimally invasive techniques achieve satisfactory outcomes in the treatment of humeral surgical neck fractures. IMN fixation offers advantages in operative efficiency, fracture healing, and early functional recovery, while MIPO with locking plate fixation appears superior in restoring long?term shoulder range of motion. Clinical choice should be individualized based on patient?specific conditions.