Proximal humeral fractures are common osteoporotic fractures, accounting for about 10% of the elderly fractures and 39.7% of adult humeral fractures. Consensus has been reached on the preferred surgical treatment for complex and unstable proximal humerus fractures. However, there are still disputes on which internal fixation method is more scientific and reasonable. In the case of osteoporosis, and medial comminuted fractures which lack of support, locking plate fixation is prone to secondary varus deformity and neck-shift angle loss. Some scholars reported that the curative effect of third-generation straight intramedullary nail in the treatment of Neer part-2, part-3 and part-4 proximal humeral fractures were satisfactory. Objective To investigate the technical application and clinical efficacy of MultiLoc intramedullary nail in the treatment of Neer part-2, part-3 and part-4 proximal humeral fractures.

From December 2017 to December 2019, 70 patients with proximal humeral fractures admitted to our trauma center were included in this study. There were 24 males and 37 females with an average age of (58.02±13.44) years (23 to 81 years) . According to Neer classification, there were 17 cases of part-2 fractures, 28 cases of part-3 fractures and 16 cases of part-4 fractures. The gender, age, intraoperative blood loss, operation duration, clinical healing time of fracture, subjective shoulder score system (SSRS) and UCLA shoulder score (Ellman method) was recorded.

All the patients were followed up for an average of 6.7 months (3 to 22 months) , and there were no complications occurred, such as internal fixator fracture, infection, humeral head necrosis, varus deformity, screw cut-out, etc. Only 2 cases had subacromial impingement syndrome. All patients obtained clinical healing, and the mean healing duration was (13.93±1.79) weeks (11 to 18 weeks) . There were no significant differences in gender and clinical duration for fracture union, but the comparison results of age, blood loss, operation duration, SSRS scoring, and UCLA score had significant difference (P<0.05) . According to UCLA scoring system, the overall excellent and good rate was 80.3%, among which the excellent and good rate of Neer part-2 and part3 fractures was 86.7% while it was 62.5% in Neer part-4 fractures.

The curative efficacy of MultiLoc intramedullary nail for proximal humeral fractures of Neer part-2 and part-3 is satisfactory. For some of Neer part-4 fractures, the curative effect is satisfactory, but the overall effect was relatively poor.