Risk factors for nonunion following open reduction and internal fixation for proximal humerus fractures.

PURPOSE: The incidence of proximal humerus fractures (PHF) is rising and surgical intervention carries risk for fracture nonunion. The purpose was (1) to compare patient demographics of those that developed nonunion and (2) identify patient risk factors that predispose to nonunion following open reduction and internal fixation (ORIF) for PHF.

METHODS

A retrospective review of the Medicare Claims Database from 2005 to 2014 for patients who underwent primary ORIF for PHFs. Patients who developed nonunion were identified as the study group (n = 1020) and compared to a control group (n = 51,209). Primary endpoints were to compare demographics of the study group and the comparison cohorts and to identify patient-related risk factors associated with nonunion within 6-months following the index procedure. A logistic regression model was constructed to determine the association of comorbid conditions on developing a nonunion. A p value of 0.001 was the significance threshold.

RESULTS

Patients who developed nonunion were younger, more likely to be male, and had higher Elixhauser-Comorbidity Index scores (7 vs. 5; p < 0.0001) when compared with controls. Iron deficiency anemia (OR: 1.32; p = 0.0001), tobacco use (OR: 1.32; p = 0.0004), rheumatoid arthritis (OR: 1.29; p = 0.0001), depression (OR: 1.28; p = 0.0002), and BMI range from 30-39 kg/m2 (OR: 1.21; p = 0.001) were significant risk factors for nonunion.

CONCLUSIONS

Certain patient risk factors including tobacco use, iron deficiency anemia, rheumatoid arthritis, depression, and a BMI in the range of 30-39 were associated with nonunion within 6 months of ORIF for PHF. This study may help in the risk stratification of these patients.