Objective:To investigate the clinical effect of locking plate combined with large autologous iliac bone implantation in treatment of complex proximal humeral fractures with comminuted proximal humerus and bone defect.Methods:A retrospective case-control study was conducted to analyze the clinical data of 52 elderly patients with proximal humeral fracture accompanied by comminuted and bone defect admitted to General Hospital of Jizhong Energy Xingtai Mining Group from January 2014 to March 2017. including 24 males and 28 females, aged 65-79 years, with an average age of 69 years. There were 36 patients with Neer's three-part fracture and 16 four-part fracture. Twenty-two patients were treated using locking plate combined with large autologous iliac bone graft (plate+ bone graft group), and 30 patients were treated using locking plate alone (plate group). The deltoid-pectoralis major approach was used in both groups. Operation time, bleeding volume and bone healing time were recorded. neck-trunk angle and shoulder joint range of motion were measured at the last follow-up . MOS 36-item short-form health survey (SF-36) score and visual analog scale (VAS) score were used to evaluate shoulder joint function and pain at last follow-up. Complications were observed as well.Results:All patients were followed up for 6-24 months, with an average of 17. 8 months. Operation time was (120.3±12.5)minutes in plate+ bone graft group, and (115.6±5.8)minutes in plate group ( P<0.01). Intraoperative bleeding volume was (400.8±15.8)ml in plate+ bone graft group and (300.2±16.2)ml in plate group ( P<0.05). Bone healing time was (2.2±0.5)months in plate+ bone graft group and (2.5±0.5)months in plate group ( P>0.05). At last follow-up, the neck-trunk angle was (132.3±10.6)°in plate+ bone graft group and (121.1±4.5)° in plate group ( P<0.01); the uplift and external rotation of shoulder joint was (149.2±3.7)° and (35.2±2.9)° in plate+ bone group, better than that in plate group [(135.1±2.1)°, (27.8±4.5)°] ( P<0.05). Meanwhile, the abduction and extension of shoulder joint was (118.4±13.9)°and (36.1±1.8)°in plate+ bone graft group, not significantly different from that in plate group [(110.8±21.9)°, (32.8±1.3)°] ( P>0.05). SF-36 score and VAS score in plate+ bone graft group was (87.3±4.7)points and (1.3±0.6)points, with significant difference from that in plate group [(70.9±7.2)points, (2.1±0.7)points]( P<0.05 or 0.01). One year after operation, 3 patients with humeral head varus and 1 patient with humeral head necrosis were observed in plate group, with the complication incidence of 13% (4/30); while 1 patient with absorption of humeral greater tuberosity in plate+ bone graft group, with complication incidence of (5%, 1/22) ( P<0.05). Conclusion:For complex proximal humeral fractures with comminuted proximal humerus and bone defect, locking plate combined with large autologous iliac bone implantation can maintain intraoperative reduction, avoid loss of neck-shaft angle, improve shoulder joint range of motion, promote function recovery, attenuate pain and reduce incidence of complications.