A Break-Even Cost-effectiveness Analysis for Venous Thromboembolism Prophylaxis in Achilles Tendon Repair Surgery

Background. Venous thromboembolism (VTE) is a potentially life-threatening complication following orthopaedic surgery. While prophylaxis is well-established in joint arthroplasty, its role after Achilles tendon repair remains controversial. Despite being a soft-tissue procedure, prolonged postoperative immobilization increases VTE risk, with some studies reporting symptomatic rates as high as 7%. However, no prior studies have assessed whether pharmacologic VTE prophylaxis breaks-even in this population. Methods. A literature review and the TriNetX Research Network were used to identify symptomatic VTE rates within 30 days of primary Achilles tendon repair without pharmacologic prophylaxis. The cost of treating a symptomatic VTE was estimated from published data and adjusted to 2025 US dollars. Retail drug pricing was obtained from an online pharmacy database. A break-even analysis was conducted to determine the absolute risk reduction (ARR) and number needed to treat (NNT) required for aspirin (81 mg and 325 mg), warfarin (5 mg), enoxaparin (40 mg), and rivaroxaban (20 mg) to be cost-effective. A sub-analysis compared postoperative bleeding and transfusion rates in patients who received chemoprophylaxis versus those who did not. Results. Among 8935 patients undergoing Achilles tendon repair without chemoprophylaxis, 47 developed a symptomatic VTE (0.526%). Aspirin and warfarin broke-even across all VTE rates, with NNTs ranging from 9217 to 10 547. Warfarin still broke-even when including international normalized ratio (INR) monitoring costs. Enoxaparin and rivaroxaban only broke-even at the highest VTE rate (7.2%), with NNTs of 131 and 390, respectively, and required higher VTE treatment costs to be justified. Conclusion. In this study, we found that aspirin 81 mg, aspirin 325 mg, and warfarin break-even for VTE chemoprophylaxis following Achilles tendon repair. Enoxaparin and rivaroxaban failed to break-even. Chemoprophylaxis decisions should be individualized, weighing patient risk and economic considerations.