Abstract: Objective: To describe long-term results of locking plate used for the treatment of non-osteoporotic fresh three- and four-part proximal humeral fractures with at least 2 years follow-up. Methods: The functional outcomes and the complications of non-osteoporotic three- and four-part fresh proximal humeral fractures treated with locking plate were assessed retrospectively. The active range of motion, the Constant score, the University of California at Los Angeles (UCLA) shoulder score, the visual analogue score (VAS) were employed to evaluate the postoperative shoulder function, and the radiographic images were taken to evaluate the neck-shaft angle of the proximal humeral and postoperative implant-related complications. Results: From January 2007 to October 2014, 107 consecutive fresh three- and four-part non-osteoporotic fresh proximal humeral fractures were treated with a locking plate in our department. Among them, 67 patients completed at least 2 years follow-up. The average follow-up time was (43.9±23.3) months (range: 24-108 months). The mean Constant score was 87.1±11.7 (range: 51-100), the mean UCLA score was 30.5±3.9 (range: 18-35), the mean VAS score was 1±2 (range: 0-7). The mean active forward flexion was 159.0°±19.3° (range: 80°-180°), the mean external rotation was 36.8°±19.5°(0°-80°) and the mean internal rotation was T11 level (T2-LS level). There were 11 patients who suffered from complications. Screw perforations were observed in 5 (7.5%) patients, avascular necrosis of the humeral head was observed in 9 (13.4%) patients and traumatic osteoarthritis was observed in 5 (7.5%) patients. Six patients showed two or more complications. There was no significant difference in outcomes when comparing the patients with three-part fractures (31 patients) with those with four-part fractures (36 patients). The rates of complications and avascular necrosis were significantly higher in the four-part fracture group than in the three-part fracture group. Conclusion: The locking plate is an effective method in treating three- and four-part non-osteoporotic fresh proximal humeral fractures. Strict surgical indication and precise surgical skill are the key points for successful treating non-osteoporotic fresh proximal humeral fractures. There is a higher rate of complications and avascular necrosis of the humeral head in the four-part fractures than in the three-part fractures.

Key words: Locking plate, Humeral fractures, proximal, Treatment outcome, Postoperative complications