A Study of Coagulation Changes at Early Stage after Total Knee Arthroplasty.

Coagulation changes after total knee arthroplasty (TKA) can provide evidence for optimization of timing of perioperative anticoagulation medicine. To evaluate the changes, 50 patients with knee osteoarthritis or rheumatoid arthritis were recruited for the study and underwent thrombelastography tests pre-, 6 hours, 12 hours, and 24 hours after TKA surgery and Doppler ultrasound examination 20 to 24 hours after surgery. The results have shown prolonged clotting time (R value) at 6 and 12 hours, while shortened at 24 hours. Similar results have been found in combined clotting and coagulation time (R + K value). However, other parameters, such as coagulation time (K value), coagulation speed (α angle), maximum amplitude (MA), and coagulation index (CI), have not significantly changed except that CI has increased significantly at 24 hours. Further Doppler ultrasound examination did not detect any deep venous thrombosis in all patients. The data showed that coagulation time after TKA within 12 hours, especially within the 6-hour time period, after surgery was significantly higher, while at 24 hours it became lower than the preoperation time. The results suggested that anticoagulation medicine is not necessary during the first 6 to 12 hours, but is required between 12 and 24 hours after surgery to reduce the risk of thrombosis.