Intrinsic and extrinsic risk factors for nonunion after nonoperative treatment of midshaft clavicle fractures.
BACKGROUND
The optimal treatment of midshaft clavicle fractures remains controversial. Nonunion is usually considered to be an uncommon complication following a nonoperatively treated clavicle fracture.


HYPOTHESIS
Not every midshaft clavicular fractures shares the same risk of developing nonunion after nonoperative treatment. The present study was performed to identify the intrinsic and extrinsic independent factors that are independently predictive of nonunion in patients with midshaft clavicular fractures after nonoperative treatment.


MATERIALS AND METHODS
We performed a retrospective study of a series of 804 patients (391 men and 413 women with a median age of 51.3 years) with a radiographically confirmed midshaft clavicle fracture, which was treated nonoperatively. There were 96 patients who underwent nonunion. Putative intrinsic (patient-related) and extrinsic (injured-related) risk factors associated with nonunion were determined with the use of bivariate and multivariate statistical analyses.


RESULTS
By bivariate analysis, the risk of nonunion was significantly increased by several intrinsic risk factors including age, sex, and smoking and extrinsic risk factors including displacement of the fracture and the presence of comminution (P<0.05 for all). On multivariate analysis, smoking (OR=4.16, 95% CI: 1.01-14.16), fracture displacement (OR=7.81, 95% CI: 2.27-25.38) and comminution of fracture (OR=3.86, 95% CI: 1.16-13.46) were identified as independent predictive factors.


CONCLUSION
The risk factors for nonunion after nonoperative treatment of midshaft clavicle fractures are multifactorial. Smoking, fracture displacement and comminution of fracture are independent predictors for an individual likelihood of nonunion. Further studies are still required to evaluate these factors in the future.


LEVEL OF EVIDENCE
Level III, case-control study.
['Liu|W|W|', 'Xiao|J|J|', 'Ji|F|F|', 'Xie|Y|Y|', 'Hao|Y|Y|']
D000293:Adolescent D000328:Adult D016022:Case-Control Studies D002968:Clavicle D005260:Female D005500:Follow-Up Studies D017102:Fracture Healing D050723:Fractures, Bone D018460:Fractures, Comminuted D006801:Humans D008297:Male D008875:Middle Aged D019637:Orthopedic Procedures D012189:Retrospective Studies D012307:Risk Factors D016896:Treatment Outcome D055815:Young Adult
Risk factor Nonunion Treatment Clavicle fracture Multivariate analysis