External fixation as a definitive treatment for humeral shaft fractures. Radiographic and functional results with analysis of outcome predictors.

OBJECTIVES: To evaluate the results obtained using unilateral external fixation as a definitive treatment for humeral shaft fractures and to identify possible predictors of radiographic and functional outcomes. DESIGN: Retrospective study. SETTING: One large metropolitan hospital. PATIENTS: A consecutive cohort of 107 patients who underwent external fixation for 109 humeral shaft fractures. MAIN OUTCOME MEASURES: Union rate, time to fracture healing, and functional assessment with disabilities of the arm, shoulder, and hand questionnaire, Constant score, Mayo Elbow Performance Index, and return to prefracture sports activity at a minimum of 2 years after surgery. Comorbidities were evaluated using the Cumulative Illness Rating Scale. Multiple linear regression analysis was used to determine whether any explanatory variables were significantly associated with the outcomes. RESULTS: The union rate in 109 humeral shaft fractures was 97.2% (106/109) at a mean of 99.2 days. Two patients (1.8%) had delayed union, and 1 patient (0.9%) did not achieve union. At the latest follow-up, the mean Constant score, Mayo Elbow Performance Index, and disabilities of the arm, shoulder and hand questionnaire score was 85.6, 97.4, and 7.4 points, respectively. All patients engaged in sports activities before fracture resumed a sport activity. At the multiple linear regression analysis, obesity was directly related to a delayed healing of fracture (P = 0.010) and comorbidity was the most important determinant of the functional outcomes at follow-up (P < 0.001). CONCLUSIONS: These data support the use of unilateral external fixation as an effective therapeutic option in patients with humeral shaft fracture. Comorbidity as assessed by Cumulative Illness Rating Scale score is the most important determinant of functional outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.