Table 1 — Prevention of VTE in Patients With Isolated Lower Extremity Injuries
| Diagnostic Test for DVT | Interventions | DVTt | ||||
| Study/Year | Patients | 1Control | 1Experimental | 1Control | 1Experimental | |
| Kujath et al/1993 | Outpatients with leg injuries managed with plaster casts | DUS when cast removed | No prophylaxis | Nadroparin, approximately 3,000 U daily | 21/127 (17) | 6/126 (5) |
| Kock et al/1995 | Outpatients with leg injuries managed with plaster casts | DUS when cast removed | No prophylaxis | Certoparin, 3,000 U daily | 7/163 (4) | 0/176 |
| Lassen et al/2002 | Below-knee fractures Achilles tendon repair | Venography > 5 weeks | Placebo | Reviparin, 1,750 U daily | 29/159 (18) 6/28 (21) | 14/134 (10) 3/48 (6) |
| Jorgensen et al/20 02 | Below-knee fractures Tendon ruptures | Venography > 5 weeks | No prophylaxis | Tinzaparin, 3,500 U daily | 10/77 (13) 6/21 (29) | 8/73(11) 2/20 (10) |
Randomized clinical trials with routine screening using an objective outcome. Values given as No. of patients with DVT/total No. of patients (%).
6% and 0%. No bleeding events occurred in the 302 patients who received LMWH in these two studies. There were methodological problems with both studies, including lack of disclosure about patient selection and the method used for randomization, the presence of non-blinded interventions, high postrandomization dropout and cross-over rates, and a marked variation in study duration of between 1 to 72 days.
Prevention of Venous Thromboembolism
Two recent multicenter trials used screening venography to detect DVT in patients with lower extremity injuries after being randomized to either no prophylaxis or LMWH. In one trial, 4 40 patients with lower extremity fracture or Achilles tendon rupture were randomized to receive placebo or reviparin, 1,750 U self-administered by daily subcutaneous injection for at least 5 weeks. The DVT rates in the placebo and reviparin groups were 19% and 9%, respectively (p = 0.01). The corresponding rates of proximal DVT were 5% and 2%. Major bleeding was encountered in < 1% of patients in both groups. A second trial compared no prophylaxis to tinzaparin, 3,500 U, among 300 patients with lower extremity injuries whose conditions had been managed with plaster casts for at least 3 weeks. DVT was diagnosed in 17% of control patients and in 10% of those who received LMWH (difference not significant). The pooled DVT rate from these two trials was 18% among control subjects, and 9.6% with LMWH prophylaxis (OR, 2.1; p = 0.005). In neither trial did LMWH prophylaxis significantly reduce the risk of DVT in patients with fractures.
Patients with below-knee injuries have a 10 to 40% risk of asymptomatic DVT. Prophylaxis with LMWH reduces the frequency of asymptomatic DVT, particularly in those with tendon ruptures.