Delayed surgery can increase the preoperative DVT risk in patients with tibial plateau fractures: a retrospective association analysis

Abstract

Objective

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Deep vein thrombosis (DVT) is a serious complication in patients with tibial plateau fractures, yet the association between surgical delay and preoperative DVT risk remains insufficiently explored. This study aimed to investigate the impact of fracture-to-operation time on preoperative DVT risk in this patient population.

Methods

A retrospective association analysis was conducted on 267 patients with tibial plateau fractures treated at Quanzhou Orthopedic Hospital between January 2020 and January 2022. The primary exposure was fracture-to-operation time, and the outcome was preoperative DVT confirmed by ultrasound. Multiple regression analyses and generalized additive models were employed, adjusting for demographic, clinical, and coagulation parameters.

Results

The incidence of thrombosis before the operation for tibial plateau fractures is as high as 27.34%. Each day of surgical delay was associated with a 48% increased risk of DVT (adjusted OR = 1.48, 95% CI: 1.32–1.67). A non-linear trend was observed, with risk increasing more rapidly within the first 14 days post-fracture. Patients in the highest tertile of surgical delay had a significantly elevated DVT risk compared to the lowest tertile (adjusted OR = 35.27, 95% CI: 9.53–130.56). Subgroup analyses confirmed the robustness of this association across age groups, calcaneus traction status, and D-dimer levels.

Conclusion

Delayed surgery is associated with increased preoperative DVT risk in tibial plateau fracture patients, and this association appears stronger within the first 14 days post-injury. Early surgical intervention may mitigate this risk, supporting the need for timely management in clinical practice. However, these findings require validation in prospective studies.

Introduction

Deep vein thrombosis (DVT) is one of the most serious complications in orthopedic trauma patients [1, 2]. Recent global data indicate that the incidence of DVT in patients with tibial plateau fractures is as high as 45.4%, with preoperative DVT accounting for 23.9% [3]. In China, a multicenter study involving 47 hospitals reported a DVT incidence of 20.67% among orthopedic trauma patients [4], rising to 23% in elderly populations [5, 6].

The time from injury to surgery (TIS) represents a critical determinant of patient outcomes [7]. Delayed surgery may initiate a cascade of pathophysiological changes, including worsening soft tissue edema, increased release of inflammatory mediators, and subsequent activation of the coagulation system. Meta-analyses indicate that early surgery (within 48 h) can reduce complication rates by 31% (95% CI: 21%−40%) [8]. However, a consensus on the optimal surgical timing for minimizing DVT risk remains elusive [9].

However, current research focuses primarily on preventing postoperative DVT, whereas studies examining risk factors for preoperative DVT are limited [10, 11]. Although the post-traumatic inflammatory response, vascular endothelial injury, and immobilization are established as key factors promoting thrombosis [12, 13], the precise mechanisms by which TIS influences preoperative DVT occurrence require further elucidation [14]. Moreover, evidence regarding the optimal surgical timing for reducing DVT risk is inconclusive [15, 16]. Additionally, while hip fracture patients have been extensively studied, research specifically focusing on tibial plateau fracture patients remains relatively scarce [17, 18].

To address these gaps, we analyzed data from patients with tibial plateau fractures admitted to our institution between January 2020 and January 2022. To our knowledge, this is the first study to use generalized additive models to explore the non-linear relationship between surgical delay and DVT risk specifically in tibial plateau fractures, while also providing stratified subgroup analyses to inform patient-specific risk assessment.

Methods

Ethics approval

This study was approved by the Medical Ethics Committee of Quanzhou Orthopedic-Traumatological Hospital (Approval Number: IRB-2025-24) and conformed to the Declaration of Helsinki [19]. The requirement for informed consent was waived by the Ethics Committee because this retrospective analysis was limited to existing data collected as part of the standard preoperative treatment of tibial plateau fractures. Furthermore, data anonymization and privacy were protected. We declared that all research data were used exclusively for academic purposes and were not authorized for other uses.

Study population

This retrospective study was conducted at the Second Department of Lower Limbs, Quanzhou Orthopedic-Traumatological Hospital. The subjects were patients who were hospitalized due to tibial plateau fractures from January 2020 to January 2022.

Inclusion Criteria: (1) Unilateral closed tibial plateau fracture diagnosed according to the Expert Consensus on Diagnosis and Treatment of Tibial Plateau Fractures [20]; (2) Underwent preoperative lower extremity color Doppler ultrasonography to screen for DVT; (3) Surgery treatment with open reduction and internal fixation using plates and screws.

All eligible patients meeting the above criteria were included in the analysis and were subsequently stratified into DVT and non-DVT groups based on the ultrasound results.

Exclusion Criteria: (1) Patients who undergo emergency surgery, such as open injuries or Schatzker I-III tibial plateau fractures with good local soft tissue conditions; (2) Old fractures (> 22 days from injury) or pathological fractures; (3) Pre-existing severe coagulation disorders or recent anticoagulation therapy (within 7 days prior to admission); (4) Significant bleeding tendency, such as in cases of subarachnoid hemorrhage; (5) Incomplete or demonstrably erroneous clinical data. Data were independently extracted from the hospital’s electronic medical record system by two trained researchers. Discrepancies were resolved through discussion with a senior researcher.

Definition and classification of thrombus

The diagnostic criteria of thrombosis were referred to our previous study [21]. Preoperative screening of deep venous thrombosis of the lower extremities was completed by an experienced sonographer using an Affiniti 50 color Doppler ultrasound medical diagnostic instrument (Philips Company, USA, Certificate number: 21086914 K). Ultrasound examinations were performed as part of standard preoperative assessment by two experienced sonographers, each with over five years of experience, following institutional protocol. During the operation, the affected limb was placed in the mild external rotation position, and the principle of intermittent compression was used to perform ultrasound examination of the deep veins of the lower extremity with L12-5 probe (frequency set at 36 Hz). From the midpoint of the groin, the examination sequence was: common femoral vein, femoral vein, popliteal vein, posterior tibial vein, peroneal vein and calf muscular venous plexus. The positive determination of deep vein thrombosis can meet one of the following [22]: (1) Color Doppler ultrasound only detected a small amount of blood flow signal, or even no blood flow signal; (2) The venous lumen was slightly compressed or even closed. The location, degree, side and accompanying symptoms of thrombus were recorded in detail.

Futhuermore, thrombosis can be divided into three categories according to the location [23]: (1) Proximal thrombosis: femoral vein, superficial femoral vein, iliac vein and popliteal vein; (2) Distal thrombosis: peroneal vein, anterior tibial vein, posterior tibial vein and intermuscular vein; (3) Mixed thrombosis: containing both proximal and distal thrombosis.

Treatment of thrombosis

According to the “Expert Consensus on the Prevention and Treatment of Venous Thromboembolism during the Perioperative Period of Accelerated Recovery after Major Orthopedic Surgery” [24], the Caprini assessment scale [25] was used to assess the thrombosis risk of inpatients. For patients with a high risk of deep vein thrombosis in the lower extremities and no contraindications to anticoagulation, low-molecular-weight heparin calcium injection (Sibolli, Shenzhen Saibaoer Biopharmaceutical Co., Ltd., 2,000 Axa IU, once daily) was administered subcutaneously, combined with ankle pump pneumatic therapy (30 min, twice a day) to prevent thrombosis. All patients completed the color Doppler ultrasound examination of the deep veins of the affected lower limb within 12 h after admission. Patients diagnosed with DVT at admission received therapeutic anticoagulation and were included in the analysis. If positive for deep vein thrombosis, they were immediately switched to low-molecular-weight heparin calcium injection (100 Axa IU/kg, twice daily) subcutaneously, and the ankle pump pneumatic therapy was stopped. After 3 days of treatment, duplex color Doppler ultrasound of the lower extremities was rechecked irregularly every 2 days until the thrombus dissolved and disappeared. For patients with proximal thrombosis or mixed thrombosis that could not be dissolved for a long time, a consultation by vascular surgeons was conducted for assessment and individualized treatment was given. In cases where necessary, a lower extremity deep vein filter was implanted before the operation. Anticoagulant drugs were discontinued one day before the surgery and on the day of the surgery. After the surgery, patients were orally administered rivaroxaban tablets (treatment dose 20 mg/once; prevention dose 10 mg/once, once daily) for anticoagulation treatment for at least one month.

Variables

Primary Exposure: The time from fracture to surgery was defined as the interval (days) between the documented time of fracture occurrence (from admission records) and the recorded start time of surgery (from operative records). The admission to operation time (days) was also recorded as a supplementary variable. Primary Outcome: The occurrence of preoperative lower extremity deep vein thrombosis (DVT), diagnosed via lower extremity color Doppler ultrasonography. Ultrasound examinations were performed and interpreted independently by two sonographers, each with over five years of experience.

Covariates: Potential confounding variables included: (1) Demographic characteristics: sex, age, and weight; (2) Clinical characteristics: fracture side, calcaneal traction, concomitant fractures, hypertension, diabetes, arrhythmia, current smoking, alcohol consumption, and Schatzker fracture classification; (3) Coagulation parameters: Prothrombin time(PT), international normalized ratio(INR), prothrombin time activity, activated partial thromboplastin time(APTT), fibrinogen, thrombin time, antithrombin, fibrin degradation products(FDP), and D-dimer levels.

Covariates were selected based on existing literature and clinical expert consensus regarding their potential influence on DVT risk [26, 27]. All laboratory tests were performed using standardized hospital methods and equipment within 24 h of admission. Missing data were less than 5% for all variables and were handled using complete case analysis.

Statistical analysis

Continuous variables were presented as mean ± standard deviation (normal distribution) or median (interquartile range), while categorical variables were expressed as frequencies or percentages. Chi-square tests were used for categorical variables, and Student’s t-test (normal distribution) or Mann-Whitney U test (skewed distribution) were employed to compare differences between groups.

The association between time from fracture to surgery and lower extremity venous thrombosis was analyzed in three steps. First, we constructed univariate and multivariate linear regression models. Three models were established: Model 1 was unadjusted; Model 2 adjusted for demographic characteristics; Model 3 further adjusted for other covariates presented in Table 1. Second, we employed generalized additive models and smooth curve fitting (penalized spline method) to evaluate the potential non-linear relationship. When non-linearity was detected, we calculated the inflection point using a recursive algorithm and constructed two-piecewise linear models on both sides of the inflection point. The log-likelihood ratio test was used to compare standard linear regression models with two-piecewise models to determine which better explained the true association.Third, subgroup analyses were performed using stratified linear regression models or generalized additive models. For continuous stratification variables, we first converted them to categorical variables based on clinical cut-points or tertiles, followed by interaction tests. Effect modification was assessed using likelihood ratio tests.

For sensitivity analysis, we converted time from fracture to surgery into a categorical variable and calculated the P for trend to verify the continuous variable analysis results and examine potential non-linearity.

The statistical software is packages R (http://www.R-project.org, The R Foundation) and EmpowerStats (http://www.empowerstats.com, X&Y Solutions, Inc., Boston, MA, USA). A two-sided P value < 0.05 was considered statistically signifcant.

Results

The occurrence of thrombosis

Among the 267 patients included in the analysis, a total of 73 thrombosis cases were detected through duplex ultrasound of the bilateral lower extremities before the operation, all of which occurred on the affected side, with an incidence rate of 27.34%. Among them, 3 cases (3.64%) were proximal thrombosis: 1 case of femoral vein, 2 cases of popliteal vein; 45 cases (61.64%) were distal thrombosis: 26 cases of intermuscular veins of the lower leg, 18 cases of posterior tibial vein, 1 case of peroneal vein; 25 cases (34.24%) were mixed thrombosis: 8 cases of posterior tibial and intermuscular veins of the lower leg, 3 cases of popliteal and posterior tibial veins, 1 case of femoral, posterior tibial veins, 1 case of posterior tibial and peroneal veins, 3 cases of posterior tibial, popliteal and posterior tibial veins, 6 cases of popliteal, posterior tibial and intermuscular veins, 2 cases of popliteal, posterior tibial and intermuscular veins. All the surgeries were carried out smoothly and no serious cardiovascular or cerebrovascular accidents such as pulmonary artery embolism or cardiac arrest occurred.

The selection of patients

During the two-year period of the investigation, a total of 397 patients with tibial plateau fractures were hospitalized in our department. Among them, 69 underwent emergency surgery and 33 received conservative treatment. Among the remaining 295 people, 3 had old fractures, 1 had a pathological fracture, 6 had received anticoagulant treatment recently, 5 had obvious bleeding tendencies, and 13 had incomplete clinical data. Ultimately, 267 patients were included in the data analysis (Fig. 1).

Fig. 1

The flowchart of patients’ selection

Description of study population results

A total of 267 patients were stratified into three groups based on the fracture-to-operation time tertiles. The demographic characteristics, including age (48.70 ± 12.76 years), weight (57.80 ± 8.78 kg), and gender distribution (approximately 1:1 ratio), were comparable among groups (all P > 0.05). Most coagulation parameters, including PT, INR, APTT, and fibrinogen levels, showed no significant differences between groups (all P > 0.05). However, significant differences were observed in FDP (56.66 ± 56.24 vs. 27.87 ± 27.91 vs. 31.35 ± 36.07 µg/mL, P < 0.001) and D-dimer levels (11.23 ± 13.97 vs. 6.37 ± 6.73 vs. 7.48 ± 9.92 mg/L, P = 0.009) among the low, middle, and high tertile groups, respectively.

The mean fracture-to-operation intervals were 3.01 ± 0.88, 6.42 ± 1.05, and 12.56 ± 3.25 days for the three groups (P < 0.001), and the analysis results of admission to operation time were similar. Notably, the utilization of calcaneus traction showed a significant increasing trend from the low to high tertile groups (7.1% vs. 20.6% vs. 47.0%, P < 0.001). The distribution of Schatzker classification demonstrated that higher types (V-VI) were more prevalent in the high tertile group (75.0%), while lower types (I-III) were more common in the low tertile group (62.9%) (P < 0.001). Most importantly, the incidence of lower limb venous thrombosis increased substantially with prolonged waiting time (10.0% vs. 13.4% vs. 53.0%, P < 0.001). No significant differences were observed in the prevalence of comorbidities (hypertension, diabetes, arrhythmia) or lifestyle factors (smoking and alcohol consumption) among the three groups (all P > 0.05). In summary, the groups were well-balanced at baseline except for expected differences in fracture severity (Schatzker classification), traction use, and markers of coagulation activity (FDP and D-dimer), which were all associated with longer surgical delays.The details of the study population are listed in Table 1.

Table 1 Baseline characteristics of patients stratified by Fracture-to-Operation time

Regression equation result

The relationship between fracture-to-operation time and deep vein thrombosis (DVT) was examined using multiple analytical approaches. In the continuous variable analysis, after comprehensive adjustment for demographic characteristics, clinical factors, and coagulation parameters, each day of surgical delay was associated with a 48% increased risk of DVT (adjusted OR = 1.48, 95%CI: 1.32–1.67, P < 0.0001). To facilitate clinical interpretation, this corresponds to an approximate [X]% absolute increase in DVT incidence for every 5-day delay in surgery.

When stratified by fracture-to-operation time tertiles, a non-linear relationship emerged. Compared to the low tertile group, the middle tertile group showed a trending but non-significant increase in DVT risk (adjusted OR = 3.13, 95%CI: 0.88–11.10, P = 0.0774), while the high tertile group demonstrated a dramatic elevation in risk with an adjusted odds ratio of 35.27 (95%CI: 9.53–130.56.53.56, P < 0.0001). The dose-response analysis further revealed that each tertile increase in surgical delay was associated with a 7.28-fold increase in DVT risk (95%CI: 3.83–13.83, P < 0.0001). The regression equation results are showed in Table 2.

Table 2 Association between fracture-to-operation time and risk of lower limb vein thrombosis

Smooth curve fitting analysis

In this analysis, we observed a significant positive correlation between the fracture-to-operation interval and the risk of venous thromboembolism. The relationship demonstrated a non-linear pattern, with the risk of VTE increasing substantially during the first 15 days post-fracture (adjusted OR 1.08 per day delay, 95% CI 1.03–1.13, p < 0.001). The risk trajectory showed a steeper increase between 5 and 15 days post-fracture, after which it plateaued slightly but maintained an upward trend. The 95% confidence intervals (represented by the outer curves) indicated statistical significance throughout the observation period, with the narrowest intervals observed between 10 and 20 days post-fracture, suggesting more precise estimates in this time range (Fig. 2).

Fig. 2

Smooth curve fitting plot of association between fracture-to-operation time and risk of venous thrombosis of lower limbs in tibial plateau fracture patients

The solid line represents the fitted probability of venous thromboembolism derived from restricted cubic spline regression analysis, with the dotted lines indicating the 95% confidence intervals. The x-axis shows the time interval from fracture occurrence to surgical intervention (days), while the y-axis represents the probability of developing venous thromboembolism. The model was adjusted for gender, age, weight, calcaneus traction, other fractures, Schatzker classification), and coagulation parameters (prothrombin time, international normalized ratio, prothrombin time activity, activated partial thrombin time, fibrinogen, thrombin time, antithrombin, fibrin degradation product and D-dimer. Each point represents individual patient data. The analysis included 267 patients who underwent surgical treatment for fractures between 2020.1 and 2022.1. The relationship demonstrates a non-linear association, with risk increasing more rapidly in the early post-fracture period (0–15 days) followed by a more gradual increase thereafter.

Analysis of saturation threshold effect model

The association between fracture-to-operation time and the risk of lower limb vein thrombosis was examined using both linear and piecewise linear regression models, with comprehensive adjustment for demographic characteristics, clinical features, and coagulation parameters. In the linear regression model, each day of delay in operation was associated with a 48% increase in the risk of lower limb vein thrombosis (OR = 1.48, 95% CI: 1.32–1.67, P < 0.0001).

To explore potential non-linear relationships, we conducted a piecewise linear regression analysis with an identified threshold at 14 days post-fracture. Before the 14-day threshold, each additional day of delay was associated with a 57% increase in thrombosis risk (OR = 1.57, 95% CI: 1.35–1.82, P < 0.0001). Beyond 14 days, the association became weaker and statistically non-significant (OR = 1.20, 95% CI: 0.87–1.67, P = 0.2704). However, the likelihood ratio test (P = 0.205) indicated that the piecewise linear model did not provide a significantly better fit compared to the simpler linear model, suggesting that the relationship between operation delay and thrombosis risk could be adequately described by a linear association. Although a threshold at 14 days was identified, the piecewise model did not significantly improve fit over the linear model. The threshold effect analysis results are showed in Table 3.

Table 3 Threshold effect analysis of fracture-to-operation time on lower limb vein thrombosis risk

Subgroup analysis

Subgroup analyses were performed to evaluate the association between fracture-to-operation time and lower limb vein thrombosis across different patient characteristics (Table 4). Our findings demonstrated a consistent positive association between prolonged fracture-to-operation time and increased risk of lower limb vein thrombosis across all subgroups, with odds ratios ranging from 1.31 to 1.52 (all P < 0.001).

In the age-stratified analysis, the strongest association was observed in patients over 60 years (OR = 1.52, 95% CI: 1.19–1.93, P = 0.0007), followed by similar magnitudes of association in patients ≤ 40 years (OR = 1.39, 95% CI: 1.13–1.72, P = 0.0021) and those aged 41–60 years (OR = 1.38, 95% CI: 1.22–1.56, P < 0.0001). However, the interaction analysis revealed no significant difference in the strength of these associations across age groups (P for interaction = 0.6477).

Regarding calcaneus traction, both patients with (OR = 1.44, 95% CI: 1.17–1.77, P = 0.0005) and without traction (OR = 1.34, 95% CI: 1.21–1.48, P < 0.0001) showed significant associations between operation delay and thrombosis risk, with no significant interaction effect (P for interaction = 0.6734). Similarly, across D-dimer tertiles, consistent associations were observed in low (OR = 1.31, 95% CI: 1.12–1.53, P = 0.0007), middle (OR = 1.43, 95% CI: 1.20–1.70, P < 0.0001), and high (OR = 1.40, 95% CI: 1.20–1.63, P < 0.0001) tertiles, with no significant interaction effect (P for interaction = 0.4402).

These findings suggest that the association between fracture-to-operation time and lower limb vein thrombosis remains robust across different patient subgroups, regardless of age, calcaneus traction status, or D-dimer levels. The absence of significant interaction effects indicates that these patient characteristics do not substantially modify the relationship between surgical timing and thrombosis risk.

Table 4 Subgroup Analysis of Association Between Fracture-to-Operation Time and Lower Limb Vein Thrombosis

Discussion

In this retrospective association analysis of 267 consecutive patients with tibial plateau fractures, we investigated the association between fracture-to-operation time (exposure) and the risk of lower limb deep vein thrombosis (outcome). After comprehensively adjusting for multiple confounding factors and performing rigorous statistical analyses, we found that each day of surgical delay was associated with a 48% increased risk of DVT (adjusted OR = 1.48, 95%CI: 1.32–1.67). Furthermore, when stratified by fracture-to-operation time tertiles, patients in the highest tertile had a substantially elevated risk of DVT compared to those in the lowest tertile (adjusted OR = 35.27, 95%CI: 9.53–130.56.53.56). However, the large odds ratio observed in the highest tertile may be influenced by residual confounding and should be interpreted with caution.

Our findings on the association between surgical timing and DVT risk align with several previous studies while also providing unique insights. The observed 48% increase in DVT risk per day of surgical delay is consistent with Zhu et al.‘s prospective cohort study, which reported that delayed surgery significantly increased DVT risk in tibial plateau fracture patients. Their study, which had a similar design but a larger sample size (n = 1179), demonstrated comparable findings, although they employed a different statistical approach, focusing on categorical time intervals rather than continuous analysis [28]. Our study extends these findings by utilizing continuous analysis and advanced non-linear modeling.

The non-linear relationship we identified, characterized by a threshold effect at 14 days post-fracture, adds nuance to existing literature. This non-linear relationship, characterized by a steeper risk increase within the first two weeks, aligns with the established orthopedic concept that the early post-injury period is a critical window of heightened inflammatory and hypercoagulable states. As summarized in the review by Tang et al., performing early definitive fixation during this vulnerable period in unstable patients can exacerbate the systemic inflammatory response and increase complication rates [29]. Our findings extend these observations by demonstrating that the risk increase was steepest within the first 14 days (OR = 1.57, 95%CI: 1.35–1.82), plateauing thereafter. However, it is important to note that the piecewise linear model did not provide a significantly better fit than the linear model, suggesting the observed non-linearity should be interpreted as a trend.

However, our results differ from some previous findings in risk magnitude and temporal patterns. Ling et al.‘s propensity score-matched analysis reported a lower DVT incidence and identified different risk thresholds [30]. Several factors may explain this discrepancy: First, their study included multiple trauma types beyond tibial plateau fractures, which could have diluted the specific risk patterns associated with this injury. Second, their patient population differed in demographic characteristics and comorbidity profiles, which might influence thrombosis risk. Third, their study used a different definition of surgical timing (employing different starting points), making direct comparisons challenging.

Recent advances in machine learning have improved DVT risk prediction in orthopedic trauma patients [31], further underscoring the importance of surgical timing in risk stratification. The strong association we observed between surgical delay and DVT risk can be explained by established pathophysiological mechanisms. Yang et al.‘s retrospective cohort study demonstrated that prolonged immobilization causes venous stasis and endothelial dysfunction, while trauma-induced inflammation promotes a hypercoagulable state via increased production of pro-inflammatory cytokines and tissue factor expression [32]. Our observation of significantly elevated FDP and D-dimer levels in patients with longer surgical delays supports this mechanism, suggesting enhanced fibrinolytic activity in response to increased thrombotic burden.

The clinical implications of our findings are substantial. Our study provides a unique contribution to the existing literature by establishing a clear temporal relationship between surgical timing and DVT risk, along with precise risk estimates to guide clinical decision-making. Identifying a non-linear trend around 14 days clinicians with a concrete timeframe for surgical intervention, while our subgroup analyses offer valuable insights for patient-specific risk stratification [33]. These results suggest that implementing standardized early surgery protocols, particularly within 14 days post-injury, may reduce DVT risk in tibial plateau fracture patients. For high-risk patients, especially those over 60 years old or with elevated D-dimer levels, prioritizing surgical intervention within 7 days could be considered when medically appropriate. However, these recommendations should be viewed as hypotheses generated from retrospective data and require validation in prospective multicenter trials. Furthermore, our results support the development of risk-stratified care pathways and the integration of surgical timing into existing DVT prevention protocols. Future research should validate these findings through prospective multicenter trials and investigate the cost-effectiveness of early surgery protocols. Our study has methodological strengths that enhance the reliability and applicability of our findings. First, we utilized a comprehensive statistical approach combining traditional regression analyses with advanced modeling techniques, including generalized additive models and smooth curve fitting. This allowed us to detect and characterize the non-linear relationship between surgical timing and DVT risk. Second, multivariable regression adjustment effectively controlled for potential confounding factors, mitigating selection bias common in retrospective studies. Third, extensive subgroup analyses across different patient characteristics provide valuable insights for personalized surgical timing decisions [34]. The inclusion of multiple coagulation parameters and their temporal changes strengthens our understanding of the underlying pathophysiology. Additionally, standardized ultrasound assessment by two experienced sonographers ensured robust outcome measurement. Several limitations warrant consideration. First, as a single-center retrospective study, the generalizability of our findings may be limited, requiring validation in multi-center studies. Second, our exclusively Chinese study population may limit the applicability of our findings to other ethnic groups. Third, the observational design allows us to establish associations but not causal relationships between surgical timing and DVT risk [35]. Fourth, despite adjusting for numerous measurable confounders through regression models, unmeasured confounding factors might persist. Fifth, the potential for immortal time bias in retrospective analyses of time-to-surgery should be acknowledged. Sixth, our exclusion of patients with open fractures or those requiring emergency surgery may limit the generalizability of our findings. Seventh, center-specific practices, such as anticoagulation protocols and ultrasound screening frequency, may further limit the external validity of our results. Furthermore, the 22 days limit on fracture duration in our study might have excluded patients with delayed presentation, potentially affecting the comprehensive assessment of DVT risk in this subgroup.

Conclusion

Delayed surgery is associated with increased preoperative DVT risk in tibial plateau fracture patients, and this association appears stronger within the first 14 days post-injury. Early surgical intervention, particularly within 14 days of injury, may reduce DVT risk in these patients. However, this conclusion needs to be confirmed by high-quality prospective multicenter studies.