Deep venous thrombosis prophylaxis with low molecular weight heparin and elastic compression in patients having total hip replacement. A randomised controlled trial.

Seventy-eight patients having elective total hip replacement were randomised into 3 groups A) control; B) low molecular weight heparin: (enoxaparin 40 mg once daily) and C) enoxaparin (40 mg once daily) plus graduated elastic compression (TEDR stockings) for 8-12 days. All patients had a preoperative perfusion lung scan and chest X-Ray and a postoperative perfusion/ventilation scan together with bilateral ascending venography on days 8-12. A blood sample was taken preoperatively, on the 1st, 3rd and 5th postoperative day and at the end of the study. The control group received placebo injections. The venograms and V/Q scans were reported blindly by an independent panel of three and one radiologists respectively. An independent panel of assessors stopped entry in the control group when a total of 45 patients were admitted according to Ethics Committee directives. The study continued with groups B and C. The incidence of DVT (including isolated asymptomatic calf thrombi) was as follows: Group A (n = 14) 93%; Group B (n = 32) 38%; Group C (n = 32) 25% (chi 2; p < 0.001 for group A versus B or C). The incidence of proximal DVT was: Group A 57%; group B 28%; group C 13% (chi 2; p = 0.057 for group A versus B and p < 0.005 for group A versus C). The incidence of silent pulmonary embolism (PE) (new defect on V/Q scan) was 28% (8 out of 29) in patients with and 5% (2 out of 43) in patients without DVT (chi 2; p < 0.02). The combination of high TAT and low anti-Xa activity on the 1st postoperative day identified a high risk group of patients who had a 56% incidence of proximal DVT on the 8th to 12th postoperative day. Further studies are needed to confirm the suggested increased efficacy in prophylaxis by the combination of LMWH and GEC as compared with LMWH alone.