Factors associated with humeral shaft fracture nonunion

PURPOSE: This study aims to describe factors associated with risk of nonunion in patients treated for humeral shaft fracture. METHODS: Adult patients treated for humeral shaft fracture at one Level 1 center from December 2009-July 2020, screened via ICD-10 code were retrospectively reviewed. Patient characteristics and radiographic analysis were recorded. Independent samples t-test was used for continuous variables, and chi squared or fishers exact test for categorical. P < 0.05 was considered significant. RESULTS: Of 386 patients, 15.3% went onto nonunion (mean time to diagnosis 122 days). Patients with nonunion were more likely have comorbid alcoholism (p < 0.001) and hypothyroidism (p 0.048) and were significantly more likely to have been initially managed nonoperatively (p < 0.001). Mechanism was significantly associated (p 0.008). Of those with nonunion treated surgically initially, there were differences in the number and positioning of screws utilized in ORIF, including more screws distally (4.29+/− 1.86 vs. 3.77+/− 0.92, p 0.048) to the fracture through the plate, and fewer screws outside of the plate in the form of lag screws (0.41+/− 0.87 vs. 1.13+/− 1.44, p 0.045) in diagnosed nonunion. 11 patients diagnosed with nonunion required more than 1 revision procedure (mean 2.18). 27 patients diagnosed with nonunion had available documented radiographic union (range 56–872 days from date of nonunion diagnosis). CONCLUSION: Specific comorbidities, initial nonoperative management and surgical construct configuration in patients treated with ORIF are risk factors for development of humeral shaft fracture nonunion. Treatment and recovery from humeral shaft nonunion remain varied, warranting further study.