Abstract:[Objective] To analyze the characteristics and related factors of inferior glenohumeral subluxation (IGHS) after plate internal fixation of proximal humerus fractures. [Methods] A retrospective study was done on 152 patients who underwent open reduction and internal fixation (ORIF) with proximal humerus locking plate (PHLP) for proximal humeral fractures in our department from June 2018 to June 2021. The characteristics and related factors of IGHS were analyzed by univariate comparison and multivariate logistic regression. [Results] All patients had ORIF conducted smoothly, however, 58 patients (38.2%) of them were confirmed as IGHS, and the remaining 94 patients (61.8%), were proved non-IGHS based on of standing anteroposterior shoulder X-ray taken 1 week after operation. The patients in the IGHS group were immediately given high-position suspension with forearm sling, and deltoid muscle strength training, namely active and passive shrug exercise. At 1 month after ORIF, 57 patients with IFHS got subluxation disappeared. Regarding to univariate comparison, the IGHS group proved significantly higher ratio than the non-IGHS group in term of Neer type IV fracture [III/IV, (11/47) vs (82/12), P< 0.001], subluxation before surgery [yes/no, (28/30) vs (6/88), P<0.001], deltopectoral approach [deltopectoral / deltoid splitting, (44/14) vs (55/39), P=0.030], and the former consumed significantly longer operation time than the latter [(123.9±35.6) min vs (75.6±20.4) min, P< 0.001]. As results of multifactor logic regression, the longer operation time (OR=3.133, P<0.001), subluxation before ORIF (OR=2.550, P< 0.001), Neer type IV fractures (OR=2.347, P=0.023), and deltopectoral approach (OR=1.956, P<0.001) were the independent risk factors for IGHS. [Conclusion] The IGHS after ORIF with PHLP for proximal humerus fracture is a common phenomenon with good prognosis. The most important factors related to IGHS after plate internal fixation are severe fracture types, inferior glenohumeral subluxation before operation, long operation time and deltopectoral approach.