To analyze the factors that influence screw penetration after plating for proximal humerus fractures of Neer two- or three-part.

We reviewed the patients with proximal humerus fracture of Neer types Ⅱ & Ⅲ who had been treated from January 2006 to June 2017. The data were documented regarding gender, age, Neer classification, osteoporosis, surgical procedure, cephalic screw number, type of medial support and screw penetration. They were divided into 2 groups according to the presence or absence of screw penetration. χ² test and independent samples t test were used with software IBM SPSS 22.0. The multivariate logistic regression was used to identify the independent risk factors when there were two or more statistically significant factors. The two-side test was used and significance was set to P< 0.05.

Altogether 78 patients were included in our analysis, including 27 males (34.62%) and 51 females (65.38%) with an average age of 57.41 years (from 18 to 85 years).Their average follow-up time was 7.7 months (from 3 to 24 months). There were 54 Neer two-part fractures (69.23%) and 24 Neer three-part ones (30.77%). Screw penetration was observed in 18 patients (23.08%) but not in the other 60 ones (76.92%). The χ² test and independent samples t test revealed that screw penetration was significantly associated with gender (P=0.003), osteoporosis (P=0.003) and cephalic screw number (P=0.003) but not with age (P=0.256), Neer classification(P=0.754), surgical procedure( (P=0.308) or type of medial support (P=0.186). The multivariate logistic regression revealed that osteoporosis (P=0.027) and cephalic screw number (P=0.026) were independent risk factors for screw penetration.

After plating for proximal humerus fractures of Neer two- or three-part, the patients with osteoporosis and those receiving more than 5 cephalic screws may face a higher risk of screw penetration than those without osteoporosis and those receiving 4 cephalic screws.

Shoulder fractures; Postoperative complications; Bone nails; Osteoporosis