Displaced Midshaft Clavicle Fracture Union Can Be Accurately Predicted with a Delayed Assessment at 6 Weeks Following Injury: A Prospective Cohort Study.

BACKGROUND: It is unclear if clinical recovery following a midshaft clavicle fracture can accurately predict fracture-healing. The additional information that can be assessed at 6 weeks after injury may have superior predictive value compared with information available at the time of the injury. METHODS: A prospective study of all patients (>/=16 years of age) who sustained a fully displaced midshaft clavicle fracture was performed. We assessed patient demographic characteristics, injury factors, functional scores, and radiographic predictors with a standardized protocol at 6 weeks. Conditional stepwise regression modeling was used to assess which factors independently predicted nonunion at 6 months after the injury as determined by computed tomography (CT). The nonunion predictor 6-week model was compared with a previously validated model based on factors available at the time of the injury, which included smoking, comminution, and fracture displacement. RESULTS: At 6 months, 200 patients completed follow-up. The CT-defined nonunion rate was 14% (27 of 200). Of the functional scores, the QuickDASH (the abbreviated version of the Disabilities of the Arm, Shoulder and Hand questionnaire) had the highest accuracy on receiver operator characteristic (ROC) curve analysis with a 39.8-point threshold, above which was associated with nonunion (area under curve [AUC], 76.8%; p /=40 points (p = 0.001), no callus on radiographs (p = 0.004), and fracture movement on examination (p = 0.001) were significant predictors of nonunion. If none were present, the predicted nonunion risk was 3%, found in 40% (80 of 200) of the cohort. Conversely, if >/=2 of the predictors were present, found in 23.5% of the cohort, the predicted nonunion risk was 60%. The nonunion predictor model at 6 weeks appeared to have superior accuracy (AUC, 87.3%) when compared with the nonunion predictor model at the time of injury (AUC, 64.8%) for fracture-healing on ROC curve analysis. CONCLUSIONS: Delayed assessment at 6 weeks following displaced midshaft clavicle fracture enables an accurate prediction of patients who are likely to have union with nonoperative management. One in 4 patients are at an increased risk of nonunion and may benefit from operative intervention. LEVEL OF EVIDENCE: Prognostic Level I. See Instructions for Authors for a complete description of levels of evidence.