CRP and deep vein thrombosis: This study has three key highlights: (i) it used the largest prospective cohort of closed DFFs patients diagnosed by DUS for DVTs; (ii) DVT location analysis and their prognosis over 2 months were performed; and (iii) ROC analysis was performed to identify a highly sensitive cut-off value for continuous variables, and CRP > 11 mg/L was found to be an uncommon independent protective factor for preoperative DVT after closed DFFs.