Background:Deep venous thrombosis (DVT) is a common complication of arthroplasty in old patients.We analyzed risk factors for lower-limb DVT after arthroplasty in patients aged over 70 years to determine controllable risk factors.Methods:This was a retrospective study of 1,025 patients aged ＞70 years treated with knee arthroplasty at our hospital between January 2009 and December 2013.Of 1,025 patients,175 had postoperative lower-limb DVT.We compared medical history,body mass index (BMI),ambulatory blood pressure,preoperative and postoperative fasting blood glucose (FBG),preoperative blood total cholesterol,triglyceride,high-and low-density lipoprotein cholesterol,and preoperative homocysteine (Hcy) between thrombus and non-thrombus groups.B-mode ultrasonography was used to detect lower-limb DVT before the operation and 7 days after the operation in all patients.Logistic regression analysis was used to determine risk factors for DVT.Results:Incidence of diabetes (P =0.014),BMI (P =0.003),preoperative FBG (P =0.004),postoperative FBG (P =0.012),and preoperative Hcy (P ＜ 0.001) were significantly higher in the thrombus group.A significantly greater proportion of patients in the non-thrombus group had early postoperative activity (P ＜ 0.001) and used a foot pump (P ＜ 0.001).Operative duration was significantly longer in the thrombus group (P =0.012).Within the thrombus group,significantly more patients had bilateral than unilateral knee arthroplasty (P ＜ 0.01).Multivariate logistic analysis revealed BMI,preoperative Hcy,postoperative FBG,long operative duration,bilateral knee arthroplasty,and time to the activity after the operation to be predictive factors of DVT.At 6-month follow-up of the thrombus group,4.7％ of patients had pulmonary embolism and 18.8％ had recurrent DVT;there were no deaths.Conclusions:Obesity,inactivity after operation,elevated preoperative Hey and postoperative FBG,long operative duration,and bilateral knee arthroplasty were risk factors for DVT in patients aged over 70 years.