Abstract: BACKGROUND: For complex proximal humeral fractures, internal fixation is usually used in clinical treatment. Which fixed approach has the advantage is still undecided.  
OBJECTIVE: To compare the efficacy of the 3rd generation multiloc intramedullary nail, common curved intramedullary humeral nail and proximal humeral locking plate in the treatment of complex proximal humeral fractures (Neer 3 and 4 parts).
METHODS: A total of 38 inpatients with complex proximal humeral fractures (Neer 3 and 4 parts) treated by surgery from August 2018 to March 2022 in Zhenjiang Ruikang Hospital and undergone postoperative follow-up were selected. There were 20 males and 18 females. Their ages ranged from 57 to 74 years. Of them, 13 patients received the third generation multiloc intramedullary nail fixation; 12 patients received common curved intramedullary nail fixation; 13 patients received proximal humeral locking plate fixation. Fracture healing time, visual analogue scale score, Constant-Murley shoulder score, DASH score of upper limb dysfunction, and imaging examination results were observed among the three groups in follow-up.  
RESULTS AND CONCLUSION: (1) All 38 patients were followed up for 12 to 18 months. There was no significant difference in visual analogue scale score among the three groups at 7 days after surgery (P > 0.05). There was no significant difference in fracture healing time among the three groups (P > 0.05). (2) There was no significant difference among the three groups in the angle of shoulder forward flexion lifting, external rotation, internal rotation and abduction at 1, 3, 6, and 12 months after operation (P > 0.05). The imaging examination results showed that the humeral neck shaft angle of the multiloc intramedullary nail group was greater than that of the common curved intramedullary nail group and the locking plate group at 3, 6, and 12 months after operation (P < 0.05). The humeral head varus angle and humeral head height loss were lower than those in the common curved intramedullary nail group and the locking plate group at 3, 6 and 12 months after operation (P < 0.05). (3) The Constant-Murley shoulder joint scores of the multiloc intramedullary nail group at 1, 3, 6, and 12 months after operation were higher than those of the common curved intramedullary nail group and the locking plate group (P < 0.05). The DASH scores of upper limb dysfunction at 1, 3, 6, and 12 months after operation were lower than those in the common curved intramedullary nail group and the locking plate group (P < 0.05). (4) The findings indicate that for complex proximal humeral fractures (Neer parts 3 and 4), the third generation multiloc intramedullary nail has significant advantages in anti-compression, anti-varus and maintenance of neck shaft angle fixation and has the characteristics of quick recovery of shoulder function.

Key words: the third generation multiloc intramedullary nail, common curved intramedullary nail, proximal humeral locking plate, complex proximal humeral fracture, internal fixation, shoulder function