Incidence of Deep Vein Thrombosis and Its Natural History Following Unilateral Primary Total Knee Replacement in Local Chinese Patients-A Prospective Study

Purpose: This prospective study was to investigate the incidence and the fate of deep vein thrombosis (DVT) among Chinese patients following unilateral primary total knee replacement (TKR). The influence of tourniquet time and the mode of anaesthesia on DVT were evaluated. Method: 390 patients who underwent unilateral cemented primary TKR were investigated. Patients whose body-mass-index (BMI) exceeded 30kg/m(2) were given chemoprophylaxis with low molecular heparin postoperatively. DVT was diagnosed using duplex ultrasonography on 4th to 7th days after operation. DVT was classified into two groups, distal and proximal. Patients who had DVT on the first scan were assigned two follow-up scans. Result: The incidence of DVT was 25.7%. 97 patients (24.9%) had distal DVT, whereas 3 had proximal DVT (0.8%). Among patients with DVT, 18 (18%) of them resolved at first follow up scan, 82 persisted, and there were no proximal progression. At the 6th week scanning, 57 patients (57%) were free from DVT, while 42 patients (42%) had persistent DVT. There was one (1%) case which the distal DVT had proximal migration, but there was no pulmonary embolism. Tourniquet time and mode of anaesthesia did not reveal any statistical significance on the incidence of DVT. Conclusion: This prospective study showed that the incidence of DVT after unilateral primary TKR in Hong Kong Chinese patient was high. However, most of them are distal to popliteal vein with low risk of proximal migration. More than half of them resolved at about two months after the operation.