The efficacy and safety of low molecular weight heparin (LMWH), unfractionated heparin (UFH) and warfarin for prophylaxis of thrombo-embolism in orthopaedic surgery were compared using meta-analysis techniques. Twenty-two studies were included, 2 of which compared LMWH to warfarin. The mean probabilities to develop deep-vein thrombosis (DVT), pulmonary embolism and major and minor bleeding using UFH were: 0.21 (95% confidence interval, CI: 0.18-0.24); 0.01 (95% CI: 0.01-0.02); 0.05 (95% CI: 0.03-0.07), and 0.19 (95% CI: 0.17-0.22), respectively. The relative risk (RR) of DVT for LMWH vs. UFH was 0.76 (95% CI: 0.60-0.91), p < 0.05 and for LMWH vs. warfarin 0.78 (95% CI: 0.69-0.87), p < 0.05. The RR of minor bleeding for LMWH vs. UFH was 0.76 (95% CI: 0.64-0.92), p < 0.05. The RR of minor bleeding for LMWH vs. warfarin was 3.28 (95% CI: 2.21-4.70), p < 0.05.
Conclusion: in orthopaedic surgery, LMWH is significantly superior to both UFH and warfarin in the prevention of DVT and results in significantly less minor bleeding complications when compared to UFH, but significantly more minor bleeding when compared to warfarin.