Efficacy analysis of double plate internal fixation for treating medially unstable comminuted proximal humeral fractures: a retrospective study

In medially unstable proximal humeral fractures, lateral locking plate fixation alone frequently provides inadequate stability, resulting in varus collapse and poor shoulder function. The adjunctive use of an anteromedial locking plate may achieve better clinical results. To investigate the clinical efficacy of lateral combined with anteromedial double-plate internal fixation in the treatment of medially unstable comminuted proximal humeral fractures by comparing it with the proximal humeral lateral locking plate treatment. From January 2022 to July 2024, a total of 40 patients with medially unstable comminuted proximal humeral fractures who met the selection criteria were retrospectively included in this study. These patients were divided into two groups according to the internal fixation method they received: Group 1 and Group 2, with 20 patients in each group. Group 2 received treatment involving lateral combined with anteromedial double-plate internal fixation, while Group 1 underwent treatment with a proximal humeral lateral locking plate for the same type of fracture. This study aims to compare the operation time, intraoperative blood loss, postoperative hemoglobin levels, incision length, hospital stay, fracture healing time, and complication rates between the two patient groups. Additionally, we will assess changes in the neck-shaft angle at 1 week, 1 month, 3 months, 12 months，and 24 months postoperatively, as well as the postoperative shoulder Constant-Murley score and the American Shoulder and Elbow Surgeons (ASES) score between the two groups. No significant intergroup difference was observed in the change of neck-shaft angle at 1 week and 1 month postoperatively. In contrast, at 3, 12, and 24 months, Group 2 exhibited significantly less collapse of the neck-shaft angle compared with Group 1 (P<0.05). Baseline and 1-week postoperative Constant-Murley and ASES scores were similar between groups. At all later time points (1, 3, 12, and 24 months), both functional scores were significantly higher in Group 2 than in Group 1 (P<0.05). In Group 1 and Group 2, the Constant-Murley and the ASES scores at 1, 3, 12, and 24 months postoperatively were significantly higher than those recorded at 1 week postoperatively (P<0.05). Additionally, both scores in both groups at 1 week and 1 month postoperatively were significantly lower than those at 3 months postoperatively (P<0.05). Lateral combined with anteromedial double-plate fixation significantly enhances medial stability and improves shoulder function in patients with medially unstable comminuted proximal humeral fractures.