In this study, we retrospectively investigated the common risk factors for DVT after knee arthroscopic PCL reconstruction in patients with PCL injury alone and excluded the potential impacts of multiple ligaments injury. By the multivariate analysis, an elevated BMI value (BMI ≥ 25 kg/m2) was associated with a 0.49-fold increased risk of DVT postoperatively. Also, postoperative DVT risk in patients with an increased D-dimer level was also 3.82 times higher than that in controls. It further indicated that both high BMI and D-dimer values might have underlying effects on post-surgery DVT in these patients.
In recent years, obesity has been proven to be an independent risk factor for VTE, which is often accompanied by disturbances of lipid metabolism such as increased TG or reduced high-density lipoprotein (HDL) cholesterol levels. Previously, Griffin et al. and Mineo et al. pointed out that HDL could inhibit platelet aggregation, reduce blood viscosity, enhance protein C anticoagulation mechanism, and reduce VTE formation by acting on vascular endothelium. Simultaneously, low-density lipoprotein could promote the expression of thrombin, tissue factor, factor VII and X, and accelerate the activation of platelets to induce the formation of VTE. Also, TG could increase the production of coagulation factors VII, VIII, IX, and plasminogen activation inhibitory factor-1, partially exerting a prothrombotic effect on thrombosis[15, 17]. All these findings further suggested that the high BMI may eventually play a partial role in the development of VTE by affecting lipid metabolism which could acted on the coagulation and fibrinolytic system. As a kind of commonly used lipid-lowering drugs, statins have been confirmed to reduce the risk of VTE potentially[18–20]. Importantly, Delluc et al. indicated that the anti-VTE effect of statins is likely due to its direct actions on the systemic coagulation mechanism. Previously, it has been suggested that the increase in subcutaneous fat and visceral fat caused caused by obesity can promote the secretion of multiple pro-inflammatory factors and mediators such as C-reactive protein, tumor necrosis factor-α, interleukin-6, and interleukin-18. Also, Rodriguez et al. remarkably proposed that statins might reduce the occurrence of VTE by down-regulating the expression of inflammatory mediators. Summarily, these existing research results ulteriorly illustrated that the low-grade inflammatory state associated with obesity itself was very likely to be a major reason for the increased risk of VTE. Although the specific association of a high BMI and VTE is still not clear, for the obese patients with PCL injury, there is quite a necessity to take some measures exactly as strengthening physical prevention, taking lipid-lowering medication, and anticoagulant intervention for a decrease in DVT incidence after knee arthroscopic PCL reconstruction.
D-dimer is widely used in clinical practice as an indicator to monitor DVT with a high sensitivity and specificity. Although the D-dimer level is affected by inflammation, bleeding and some other factors, effective anticoagulation is still necessary for patients with high D-dimer levels after knee arthroscopic PCL reconstruction. Considering the fact that the hypercoagulable status of patients after surgery usually lasts no more than 48 hours which is the peak period of the formation of acute DVT in the lower limbs, the blood D-dimer level was routinely measured on postoperative day 3 in this study and then the ultrasound of both legs was performed. This might largly ensure the reliability and accuracy of our findings. Follow-up studies will continue to be focused on the monitoring of D-dimer levels in such patients in order to better predict and assess the initiation, progress and outcome of postoperative DVT.
The incidence rates of symptomatic and asymptomatic DVT were 5.81% (5/86) and 9.30% (8/86) respectively, which were also close to the findings of Sun et al.. Furthermore, it was worth noting that the positive rate of Homans and Neuhof tests in DVT group was significantly higher than that in non-DVT group, which largely implied that DVT after knee arthroscopic PCL reconstruction was usually associated with some corresponding symptoms and signs. Therefore, timely and targeted anticoagulation for patients with symptoms postoperatively may reduce the risk of DVT to a certain extent. Although the long-term risk of symptomatic or asymptomatic DVT after knee arthroscopy is still unknown and allow for the relatively high incidence of asymptomatic DVT (9.30%) in this study, it is still necessary to make a clear diagnosis of DVT by using ultrasound and further perform a effective intervention. Definitely, find more specific and predictable risk factors associated with postoperative DVT is also an issue that needs to be solved.
In this study, the Doppler ultrasound of both lower limbs were used as the criteria for diagnosing DVT and the common risk factors of DVT after knee arthroscopic PCL reconstruction in patients with PCL injury were systematically analyzed. However, due to the limited sample size, we failed to do a in-depth analysis after stratified by gender. Still, there existed a lack of dynamic and continuous monitoring of postoperative DVT by ultrasound.