Prolonged Prophylaxis after Joint Replacement: Another Step Sideways?

• Heparin, low-molecular-weight
• Thrombophlebitis
• Venous thrombosis
• Arthroplasty, replacement, knee
• Arthroplasty, replacement, hip

It is generally accepted that perioperative prophylaxis against venous thromboembolism is important for patients undergoing hip and knee replacement. Even before shortened hospitalizations, there was a tendency to extend prophylaxis into the outpatient setting. If prolonged prophylaxis after joint replacement were proven safe and effective for preventing not only clots but their clinical sequelae and were also convenient and inexpensive, it would not be controversial. Unfortunately, this is not the case.

Strong clinical evidence supports the safety and effectiveness of low-molecular-weight heparin in preventing venographically demonstrable thrombosis in patients undergoing hip replacement; incidence is reduced by approximately 50% (1-6). Any clinician caring for diabetic patients, most of whom self-inject twice daily for life, cannot seriously argue that 20 to 30 days of once-daily subcutaneous self-injection at home during rehabilitation from joint replacement surgery is truly inconvenient. Therefore, the validity of prolonged prophylaxis against venous thromboembolism and the controversy surrounding it center on whether the practice prevents clinical sequelae and is worth the cost.

Into this fray step Heit and colleagues (7), with an important study that counts clinically relevant symptomatic outcomes rather than mostly asymptomatic venographic clots. They report results from 1195 patients who underwent elective hip or knee replacement in North America. Patients received the low-molecular-weight heparin ardeparin sodium (50 anti-X_aIU/kg of body weight) subcutaneously twice daily in the hospital and were then randomly assigned in a double-blind manner to receive injections of ardeparin sodium, 100 IU/kg per day, or placebo for 6 weeks after discharge. Although ardeparin …