To retrospectively analyze the prognosis and complications of patients with isolated calf intermuscular venous thrombosis after primary total knee arthroplasty, and to compare the efficacy and safety of the two anticoagulation regimens.

From January 2017 to November 2021, patients diagnosed with isolated calf intermuscular venous thrombosis after primary total knee arthroplasty in the Second Affiliated Hospital of Xi 'an Jiaotong University were collected.The patients with long-term use of anticoagulants, history of thrombosis, preoperative thrombosis, postoperative deep vein thrombosis in other parts of the lower extremities or with confirmed pulmonary embolism, the patients with high hemorrage risk but could not use anticoagulants or contraindicated to use rivaroxaban were excluded. The enrolled patients were divided into two groups according to the duration of anticoagulants: the three-month anticoagulant group, anticoagulant duration were three months; the six-week anticoagulant group, anticoagulant duration were six weeks. Both the groups were given rivaroxaban 20 mg, one time per day. All the patients were followed up for six months in one, two, six, 12 and 24 weeks after the treatment. The outcome of thrombosis, wound and complications were observed and analysed to compare the efficacy and safety of these two anticoagulant regimens for isolated calf intermuscular venous thrombosis. Independent sample t test was used for the measurement data comparison between the two groups, and chi square test was used for enumeration data.

A total of 215 patients were successfully followed up. There was no statistically significant difference in the prognosis between the two groups (P>0.05). It could be seen from the outcome data of the two groups that the incidence of proximal thrombosis spread decreased with the prolongation of time after six-week anticoagulation treatment, and the thrombolysis rate increased gradually. The incidence of hemorrage in the six-week anticoagulation group was lower than that in the three-month anticoagulation group, but there was no statistically significant difference between the two groups (all P>0.05). The incidence of wound complications in the two groups was 4.1% and 6.5% respectively, yet the difference was not statistically significant (P>0.05).

For patients with isolated calf intermuscular venous thrombosis after primary total knee arthroplasty, six weeks of anticoagulation may be effective and safe, and three months of anticoagulation is not necessary.