Background Among the causes of mortality in patients with lower extremity fracture following surgery, lower extremity deep venous thrombosis (DVT) is a leading one. To lower the morbidity and mortality, early screening and preventive anticoagulation therapy are essential in clinical study. Common screening methods, including risk prediction tools, imaging tests and D-dimer test, had various drawbacks. The study aimed to establish a new method, that is, D-dimer combined with Risk Assessment and Predictor Tool (RAPT) score, for screening the lower extremity DVT among patients with lower extremity fracture and evaluate its clinical value. Materials and MethodsThe RAPT score, plasma D-dimer and lower extremity venous ultrasonography examination reports were collected from Department of Emergency Surgery & Orthopaedic Surgery from July 2019 to December 2019, and the data were analyzed retrospectively. Regarding the lower extremity venous ultrasonography examination report as the "gold standard" to determine whether DVT exists, the sensitivity, specificity and area under the curve (AUC) of RAPT score alone, plasma D-dimer alone and combination of them in screening lower extremity DVT were analyzed and evaluated. Results 197 patients were enrolled in the study. There were significant differences in D-dimer level and RAPT score between DVT group and non-DVT group (P < 0.01). The sensitivity, specificity and AUC of RAPT score and D-dimer in screening lower extremity DVT were 78.12%, 56.44%, 0.723 and 97.71%, 25.74%, 0.803, respectively. The optimal diagnostic value of D-dimer decided by Youden's index was 1.125 μg/ml. The sensitivity and specificity of the method by combining RAPT score with this new D-dimer threshold were 96.88% and 42.57%, respectively, and AUC was 0.812. Conclusion Higher diagnostic accuracy could be achieved by combining RAPT score with new D-dimer threshold. This novel diagnostic method is potential in the clinical diagnosis of DVT among orthopedic trauma patients.