Nonunion of conservatively treated humeral shaft fractures is not associated with anatomic location and fracture pattern

Introduction Humeral shaft fractures make up 1-3% of all fractures and are most often treated nonoperatively; rates of union have been suggested to be greater than 85%. It has been postulated that proximal third fractures are more susceptible to nonunion development; however, current evidence is conflicting and presented in small cohorts. It is our hypothesis that anatomic site of fracture and fracture pattern are not associated with development of nonunion. Materials and methods In a retrospective cohort study, 147 consecutive patients treated nonoperatively for a humeral shaft fracture were assessed for development of nonunion during their treatment course. Their charts were reviewed for demographic and radiographic parameters such as age, sex, current tobacco use, diabetic comorbidity, fracture location, fracture pattern, AO/OTA classification, and need for intervention for nonunion. Results One hundred and forty-seven patients with 147 nonoperatively treated humeral shaft fractures were eligible for this study and included: 39 distal, 65 middle, and 43 proximal third fractures. One hundred and twenty-six patients healed their fractures by a mean 16 +/- 6.4 weeks. Of the 21 patients who developed a nonunion, two were of the distal third, 10 of the middle third, and nine were of the proximal third. In a binomial logistic regression analysis, there were no differences in age, sex, tobacco use, diabetic comorbidity, fracture pattern, anatomic location, and OTA fracture classification between patients in the union and nonunion cohorts. Conclusions Fracture pattern and anatomic location of nonoperatively treated humeral shaft fractures were not related to development of fracture nonunion.