Correlation between classification and secondary screw penetration in proximal humeral fractures

Objectives In this study, we investigated the correlation between fracture classification and secondary screw penetration. Methods We retrospectively identified 189 patients with displaced proximal humeral fractures treated by ORIF at our hospital between June 2006 and June 2013. All fractures were classified radiographically before surgery and follow-up for least 2 years after surgery was recommended. At each follow-up, radiographs were taken in three orthogonal views to evaluate secondary screw penetration. Results The study population consisted of 189 patients. Of these, 70 were male and 119 female, with a mean age of 59.1 years; the mean follow-up time was 28.5 months. Secondary screw penetration occurred in 26 patients. The risk of developing secondary screw penetration was 11.3-fold higher in four-part fractures than two-part fractures ( P < 0.05), 8.6-fold higher for type C fractures than type A fractures ( P < 0.05) and 11.0-fold higher for medial hinge disruption group than intact medial hinge group fractures ( P < 0.05). However there was no difference between three-part fractures and two-part fractures ( P = 0.374), and between type B and type A fractures ( P = 0.195). Age, gender, time to surgery and the number of screw in humeral head had no influence on the secondary screw penetration rate ( P > 0.05). Conclusions Patients with four-part fractures, type C fractures and medial hinges disruption are vulnerable to secondary screw penetration. This allows additional precautions to be instituted and measures to be taken as needed.