Currently, there are not reliable data on the incidence and prevalence of post-phlebitic syndrome (PTS) after an episode of asymptomatic postoperative deep vein thrombosis (DVT). In order to evaluate the epidemiology and the clinical course of PTS in patients who were submitted to hip and knee replacement, we performed a cross sectional study in orthopedic patients with previous asymptomatic postoperative DVT. For reducing potential biases, we used currently accepted and objectively documented criteria to define the clinical manifestations and severity of PTS.
Results: 98 of 217 (45.1%) patients, who underwent orthopedic surgery in the previous 2-4 years, have been included in the study. 46 of them (46.9%) had postoperative asymptomatic DVT, confirmed by venograph 23.9% satisfied criteria to be classified as having PTS. When compared with the control group (PTS 3.8%), the difference in the incidence of PTS was statistically significant (p = 0.03). The comparison of the distribution of proximal and distal thrombi in patients with PTS showed that proximal venous involvement constitutes and independent risk factor for developing PST (RR 4). We conclude that: a) about 24% of patients with previous asymptomatic postoperative DVT developed the SPT in the following 2-4 years, b) in asymptomatic DVTs, the localization of thrombi in the proximal venous segment is the most important independent risk factor for the PTS. Therefore, these results can influence the use and the choice of an adequate antithrombotic prophylaxis for reducing the incidence of postoperative proximal DVT.