Lower extremity deep vein thrombosis is a common complication of knee arthroplasty, which brings a heavy burden to patients and society[24]. In recent years, color Doppler ultrasound has been widely used in the clinical diagnosis of thrombosis because of its simplicity and reliability[25], however, there is a lag in its results. Therefore, identifying DVT risk factors can enable clinicians to timely adjust treatment measures based on patient conditions.
Nomogram can translate intricate data into predictive clinical models through mathematical modeling[16, 17]. And no study has developed a prediction model for preoperative DVT occurrence in TKA. Therefore, we compiled and analyzed the clinical data of patients who underwent TKA at our center over the past year, and constructed a user-friendly clinical prediction model based on their clinical characteristics and risk factors associated with the formation of preoperative DVT, in order to assess the risk and take appropriate interventions.
Based on previously published results, five influential factors most associated with the occurrence of preoperative DVT in TKA were screened by lasso regression and multifactorial logistic regression analyses and a nomogram was constructed. These factors included Platelet crit, Platelet distribution width, Procalcitonin, prothrombin time, and D-dimer. These predictors incorporated in the model were common and readily available. The model exhibited great predictive ability in both the training and validation sets, demonstrating robust clinical utility in foreseeing preoperative lower extremity DVT events in patients undergoing TKA.
The incidence of preoperative DVT in patients who underwent TKA in this study was 5.6%, which is similar to the results reported by Kim et al. Kim KI et al. screened 311 patients with osteoarthritis for DVT before knee arthroplasty, reporting a 4.5% preoperative DVT incidence in TKA[26]. The incidence of preoperative thrombosis has also been reported in the literature to be higher than in this study. Watanabe H et al. used 16-row multidetector computed tomography to screen for thrombosis in 71 patients undergoing knee arthroplasty both preoperatively and postoperatively, and found a preoperative thromboembolism rate of 8%[27]. Additionally, Wakabayashi H et al. used ultrasound to screen for DVT before surgery in 322 patients undergoing knee arthroplasty, revealing a notably higher incidence of 17.4% preoperative DVT[28]. The reasons for the different incidence of preoperative DVT in TKA may be related to the demographic characteristics of the study population and differences in medical history.
A number of studies have screened the risk factors for preoperative DVT formation in TKA patients, and then investigated the predictive value of individual factors for DVT formation. Xiong X et al. collected and statistically analyzed the clinical data of 458 patients who underwent TKA, discovering that several serological indices, including Platelet crit, Platelet distribution width, Procalcitonin, and D-dimer, were independent risk factors for the development of preoperative DVT in TKA patients[15]. Platelet crit, a parameter evaluating platelet count and concentration, emerges as a biomarker linked to DVT development prior to TKA[29]. Another study by Xiong X et al. concluded that a PCT > 0.228% is an independent risk factor for the development of DVT before TKA[30]. PCT plays a crucial role in regulating normal hemostasis and coagulation processes, and abnormal levels indicate potential platelet count and function irregularities, thereby elevating thrombosis risk. Platelet distribution width reflects the degree of platelet variability and is a marker of platelet activation[31]. Öztürk ZA et al. observed significantly lower PDW levels in the active phase of ulcerative colitis and Crohn's disease compared to the remission phase, suggesting that a decrease in the PDW may be related to progression or activation of the disease rather than the disease itself[32]. Ma J et al. found that a decrease in the PDW was significantly associated with the occurrence of DVT[33]. A decrease in PDW signifies heightened platelet homogeneity and increased platelet activity, potentially contributing to DVT development during hypercoagulable states in the blood. D-dimer is derived from cross-linked fibrin clots dissolved by fibrinolytic enzymes, serving as a sensitive biomarker indicative of fibrinolytic activity and coagulation function[34]. Therefore, it holds significance in thrombus screening. Stamou KM et al. noted that persistently high levels of D-dimer in the early stages of trauma not only reflect fibrinolytic activity and coagulation, but also hints at the formation of inconspicuous microthrombi[35]. However, D-dimer can be affected by a variety of factors in the body, such as trauma, infection, and tumor[36]. Our study, which excluded these confounding factors, confirm that D-dimer may be an important risk factor for preoperative lower extremity deep vein thrombosis in patients undergoing TKA. This is consistent with the findings of Jiang et al. who found that D-dimer > 0.5 µg/ml in end-stage osteoarthritis was a risk factor for DVT in patients hospitalized for TKA[37]. The mechanism behind this association may involve activated fibronectin during thrombosis, leading to increased D-dimer expression. The Prothrombin Time serves as a vital marker in coagulation screening assays, detecting the normalization of exogenous coagulation pathways and common bodily pathways[38]. Nevertheless, no study has identified the potential value of PT in predicting the risk of preoperative DVT in patients with TKA. Cao et al. compared clinical data between people who developed DVT after fracture with those who did not develop DVT after fracture and with healthy controls. They observed that the level of PT was significantly increased in the DVT group, and they noted that the optimal threshold for PT to diagnose DVT was 12.05s, with a sensitivity of 72.92% and specificity of 47.92% (AUC = 0.617, 95% CI 0.505–0.730, p = 0.048)[39]. Above all, the predictors included in our prediction model in this study were all inflammatory in previous studies, proving the validity of our study.
In conclusion, the nomogram constructed in this study has high accuracy and may play an important value in the early identification and risk prediction of preoperative occurrence of DVT in patients undergoing TKA. It provides clinicians with more favorable clinical guidance in terms of medical measure interventions. However, our study has some limitations: first, it is a single-center study with a limited sample size, which may limit its generalization and weaken the statistical analysis, thus biasing the results. Secondly, this is a retrospective study with incomplete information on some cases, and incomplete information such as lipids and thrombosis elastogram were discarded in our study, so it may not have included all potential factors affecting the occurrence of DVT. Additionally, our constructed prediction model underwent internal validation exclusively, lacking external validation across multiple centers. Thus, the applicability of our findings to broader populations undergoing TKA in various regions and countries remains uncertain, and external validation in a wider population receiving TKA is needed in subsequent studies to draw more comprehensive and reliable conclusions.