Risk Factors Associated With Nonunion After Elective Foot and Ankle Reconstruction: A Case-Control Study

Postoperative nonunion is not uncommon in the lower extremity, and significant morbidity can be associated with nonunion of the foot and ankle after surgical reconstruction. For the purposes of the present study, we retrospectively reviewed and compared a cohort of patients who had undergone elective foot and ankle reconstruction to better assess the modifiable risk factors associated with postoperative nonunion. We hypothesized that the presence of endocrine and metabolic abnormalities are often associated with nonunion after foot and ankle surgical reconstruction. We formulated a matched case-control study that included 29 patients with nonunion and a control group of 29 patients with successful fusion to assess the prevalence of certain modifiable risk factors known to have an association with nonunion after foot and ankle arthrodesis. The modifiable risk factors assessed included body mass index, tobacco use, diabetes mellitus, vitamin D abnormality, thyroid dysfunction, and parathyroid disease. A statistically significant (p < .05) difference was found between the 2 groups for endocrine and metabolic disease diagnoses in the medical records of the 58 patients identified. Thus, 76% versus 26% (p < .05) of patients experienced nonunion in the endocrine disease group versus the nonendocrine disease group, respectively. Patients with vitamin D deficiency or insufficiency were 8.1 times more likely to experience nonunion (95% confidence interval 1.996 to 32.787). No statistically significant differences were found between the groups in terms of age, sex, tobacco use, body mass index, or procedure selection (p = .56, p = .43, p = .81, p = .28, and p = 1.0, respectively). A greater prevalence of endocrine abnormalities, in particular, vitamin D deficiency and insufficiency, was associated with nonunion after elective foot and ankle reconstruction. Patients with such abnormalities appear to have a greater risk of developing nonunion after arthrodesis procedures.