Purpose: Among patients with isolated below-knee fractures, venography studies detect deep vein thrombosis (DVT) in 20 – 40%. The clinical relevance of these thrombi is unknown. We conducted the first randomized, double-blind, multicentre study designed to assess the effectiveness and safety of low molecular weight heparin compared to placebo in preventing CIVTE in patients with isolated fractures of the distal leg.

Method: Consecutive patients with fractures of the tibia, fibula or ankle requiring surgery were randomized to dalteparin 5000 U or placebo once daily SC within 72 hours of fracture for 14 + 2 days. Patients were screened using proximal duplex ultrasound at day 14, and followed up at 6 wks and 3 mos. Clinically suspected VTE was investigated using standardized algorithms with central, blinded adjudication.

Results: From August 2002 to October 2006, 134 patients were randomized to dalteparin and 131 to placebo. 98% of patients completed 3 mo follow-up. Overall, 5 patients had CIVTE (2 asymptomatic DVT, 2 symptomatic DVT, 1 nonfatal PE); 2 (1.5%) in the dalteparin arm and 3 (2.3%) on placebo (p=0.68). There were no major bleeds.

Conclusion: The overall incidence of CIVTE after surgically-repaired, isolated tibia, fibula and ankle fractures was so low (1.9%; 95% CI 0.7 to 4.7%), with no observed differences between dalteparin and placebo either for CIVTE or safety, that recruitment was stopped early. This study also demonstrates the large discrepancy between trials that utilize venographic and CIVTE outcomes.

Purpose: We conducted the first, multicentre, prospective cohort study to define the incidence of symptomatic venous thromboembolism (VTE) in patients with tibia and ankle fractures treated conservatively and relatively minor lower leg fractures. The reported incidence of deep vein thrombosis (DVT) using routine venography in patients with lower leg injury requiring cast immobilization is approximately 20–40%, which has lead to the routine use of anticoagulant prophylaxis for several weeks in many such patients. However the vast majority of venographically-detected DVTs are asymptomatic, distal thrombi whose clinical relevance is uncertain. Therefore venography is not the best outcome measure to assess the burden of clinically important VTE.

Method: Consecutive patients with tibia and fibula fractures (treated non-operatively) and patella and foot fractures, (treated operatively or conservatively) were assessed for eligibility at 5 Ontario hospitals. Patients were enrolled after informed consent within 96 hours of injury and were followed prospectively, by telephone, at 2, 6 and 12 weeks. Those with major trauma, active cancer, and previous VTE were excluded. Thromboprophylaxis was not allowed. Education regarding symptoms of VTE was provided at study entry and patients were asked about VTE symptoms at follow up. Suspected VTE was investigated in a standardized manner.

Results: From August 2002 to June 2005, 1200 patients were enrolled from 2446 consecutively screened patients. 98% of patients completed 3-month follow-up. The mean age was 45 years (16 to 93) and 60% were female. The most common fractures were fibular (39%) and most injuries were caused by falls (75%). 99 % of these fractures were unilateral. Most fractures did not require surgical repair (93%), and 82% of patients were immobilized by cast or splint for an average of 42 ±32 days. Overall, 7 patients had symptomatic, objectively confirmed VTE (2 proximal DVT, 3 calf DVT, 2 PE) with no fatal PE – an incidence of 0.6 % (95% CI 0.2 to 1.2).

Conclusion: Symptomatic VTE is an infrequent complication after these fractures without thromboprophylaxis. Therefore routine thromboprophylaxis is neither warranted, nor likely to be cost-effective in these patients. This study also highlights the significant discrepancy between clinical endpoint studies and studies using venography.