Clinical course of asymptomatic deep vein thrombosis after total knee arthroplasty in Japanese patients

Abstract

Purpose: The purpose of the present study was to follow up Japanese patients with deep vein thrombosis (DVT) after total knee arthroplasty (TKA) and also to examine factors associated with residual thrombus within the sixth postoperative month. Methods: DVT evaluation was performed by noninvasive venous ultrasonography. We retrospectively reviewed 88 Japanese patients (88 knees) receiving primary unilateral TKA, who had no preoperative DVT. We examined the influence of the following four factors on postoperative DVT: (1) patient factors (age, sex, body height, body weight, and body mass index), (2) surgical factors (operation time, bleeding amount, avascularization time, and anesthesia method), (3) postoperative factors (bleeding amount, period to ambulation, period of venous foot pump use, and ratio of graduated compression stocking use), and (4) DVT conditional factors (location, length, number of vein branches, and the presence of >5 mm vasodilatation). Results: The total prevalence of venous thromboembolism (VTE) was 62.5% (55 of the 88 patients). Among the 55 VTE patients, the rates of distal and proximal DVT were 96.4% and 3.6%, respectively. Bilateral DVT was found in 34.5%, while unilateral DVT on the surgical and nonsurgical sides were 52.7% and 12.7%, respectively. Asymptomatic pulmonary embolism was 1.8%. DVT was exacerbated in five patients (11.9%), of whom three showed additional thrombus formation. The remaining two patients had thrombus elongation or propagation from distal to proximal veins. In comparisons between thrombus-unresolved and -resolved groups within the sixth postoperative month, statistical significances were found in the incidence of bilateral DVT (50.0% vs. 15.4%, p = 0.02) and unilateral DVT (43.8% vs. 76.9%, p = 0.02). On the other hand, operation time (107.0 ± 17.3 min vs. 94.5 ± 11.9 min, p = 0.01) and avascularization time (99.8 ± 17.6 min vs. 88.0 ± 11.5 min, p = 0.01) in bilateral DVT patients were significantly longer than in unilateral ones. Conclusion: Our results suggest that an extended operation and avascularization time may be a risk factor for bilateral DVT and residual thrombus over 6 months.