Incidence of venographically proved deep vein thrombosis after knee arthroscopy.

BACKGROUND Deep vein thrombosis is a common, important complication of major orthopedic surgery, particularly knee arthroplasty. Knee arthroscopy is performed more frequently and in younger patients than knee arthroplasty. However, the true risk of deep vein thrombosis in patients who undergo this procedure is unknown. OBJECTIVE To determine the incidence of deep vein thrombosis after knee arthroscopy in a large cohort of patients. METHODS Consecutive patients scheduled for knee arthroscopy were eligible for the study. Enrolled study patients received no thromboprophylaxis. They were discharged home the day of surgery and underwent unilateral contrast venography approximately 1 week after their operation. The primary outcome measure was the incidence of venous thromboembolism. Risk factors for deep vein thrombosis were evaluated. RESULTS Among the 184 patients who had adequate venography, deep vein thrombosis was detected in 33 (17.9%; 95% confidence interval, 12.7%-24.3%). Of these, 9 were proximal (4.9%; 95% confidence interval, 2.3%-9.1%). No patient died and no patient presented with clinically suspected pulmonary embolism. Of 33 patients, only 20 (60.6%) with deep vein thrombosis had symptoms while 13 (39.4%) were asymptomatic. The risk of deep vein thrombosis was significantly higher among patients who had a tourniquet applied for more than 60 minutes. CONCLUSIONS The results of our study demonstrate that 17.9% of patients develop deep vein thrombosis after knee arthroscopy (most being either proximal or extensive). It is reasonable to perform a randomized trial to determine whether the incidence of deep vein thrombosis can be safely reduced in patients undergoing knee arthroscopy.