Quantitative index for deciding whether to administer preventive anticoagulant therapy in osteoarthritis patients undergoing total knee arthroplasty.

Abstract

The 2008 American Academy of Orthopedic Surgeons recommended that surgeons assess the relative risks of venous thromboembolism and bleeding in patients undergoing total knee arthroplasty (TKA). In this situation, a quantitative index is required for deciding whether to administer preventive anticoagulant therapy for deep venous thrombosis (DVT). In this study, we investigated the risk factors for DVT after TKA. We included 102 patients (122 knees) who underwent primary TKA for osteoarthritis of the knee between October 2007 and March 2010. DVT was evaluated using lower limb venous ultrasonography. Cutoff values for individual risk factors were determined using a receiver-operating characteristic analysis, and the patients were grouped according to the cutoff values; the odds ratios (95% CI) were also investigated. The Wilcoxon signed-rank test and χ² test were also used. DVT was positive in 25 knees (20.5%). Three risk factors for DVT after TKA were identified: age 76 years or older, preoperative maximum soleus vein (MAX-SV) diameter of 6.0 mm or greater, and preoperative D-dimer value of 1.1 μg/dl or higher. The incidence of DVT was significantly higher in the group with two or more risk factors than in the group with one or no risk factors (p = 0.0001). Development of postoperative DVT correlated significantly with the presence of the following risk factors: age 76 years or older, preoperative MAX-SV diameter of 6.0 mm or greater, and a preoperative D-dimer value of 1.1 μg/dl or higher. Considering the risk-benefit ratio, avoiding preventive anticoagulant therapy following TKA can be an option for patients with osteoarthritis with one or no risk factors.