Incidence of secondary displacement after osteosynthesis of proximal humerus fractures: a retrospective study of 185 cases

Proximal humerus fractures are the third most common fracture in patients over 65 years of age. There is no clear consensus regarding their treatment. The objective of this retrospective observational study was to calculate the incidence of secondary displacement after osteosynthesis of these fractures and to identify possible risk factors. 185 cases were reviewed and all osteosynthesized fractures between January 2008 and December 2016 were included. Data collected included age, sex, body mass index, alcohol and tobacco use, bone mineral density of the proximal humerus, fracture type, initial displacement, management time, type of treatment, surgeon's experience and expertise, and postoperative reduction quality. A radiographic follow-up was done at least 3 months following the fracture (until consolidation). The definition of secondary displacement was: varus/valgus displacement >10(degrees), tuberosity translation >5 mm, articular effraction or material breakage. 53 secondary displacements were found, with an incidence of 28.6%. Seventy-two percent were diagnosed at the first follow-up visit, which occurred at an average of 29 days postoperatively. Among all factors studied, only two were statistically significant for secondary displacement: 1) low proximal humeral bone density (defined by a Tingart index <4) appears to be a risk factor, with a calculated relative risk of 2.71 (p = 0.04); and 2) the operator's specialization in the upper limb appears to be a protective factor, with a relative risk of 0.27 (p = 0.01). A similar high incidence of complications after osteosynthesis of the proximal humerus is found in the literature, confirming the difficulty in managing these fractures. More attention should be given to patients with low bone density.