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.