Analysis of contributing factors influencing thromboembolic events after total knee arthroplasty.

BACKGROUND

Venous thromboembolic events (VTE) are a known and well-described complication following total knee arthroplasty (TKA). We sought to validate the American College of Chest Physicians thromboprophylaxis recommendations after elective TKA, paying special attention to our dose adjustments for weight, and their impact on VTE in our population.

METHODS

We retrospectively investigated risk factors in patients undergoing TKA, focusing mainly on symptomatic VTE occurrence rates from deep vein thrombosis (DVT) or pulmonary embolism (PE). The anticoagulation protocol consisted of starting low molecular-weight heparin (LMWH) therapy, with dalteparin administered 12 h after surgery in patients who received general anesthesia or 24 h later in patients who received single-dose regional anesthesia.

RESULTS

Data from 346 patients (mean age 66.8 [range 24-91] yr) who underwent primary or revision TKA depicted an overall symptomatic VTE rate of 15%. The proximal DVT rate was 1.7%, and the nonfatal PE rate was 0.9%. The mean time to VTE diagnosis was 5.6 days. The first dalteparin dose was administered 19.5 (range 10-48) h after surgery in patients without VTE and 22.6 (range 11.5-52) h after surgery in patients with VTE ( = 0.003). With a first dose of dalteparin administered 12 h postoperatively, patients presented significantly lower DVT and PE rates than if it was administered 24 h postoperatively (8.5% v. 16.3%, = 0.048).

CONCLUSION

Delayed administration of LMWH has deleteriously impacted the VTE rate after TKA at our institution. Prompt initiation of LMWH (≤ 12 h after surgery) is appropriate, without increasing the risk of major bleeding.