Incidence and Risk Factors Associated with Post Tibial Plateau Fracture Deep Venous Thrombosis: A Prospective Cohort Study

Objective: The purpose behind this study was to determine the incidence and risk factors associated with post tibial plateau fracture deep venous thrombosis (DVT) Materials and Methods: A prospective study was conducted in a tertiary care hospital, Indus Medical College & Hospital, Tando Muhammad Khan to recruit those patients who were undergoing orthopedic surgeries during the periods of eighteen months. All the adult patients of both gender planned for surgery due to tibial plateau fracture were enrolled under this study. Duplex ultrasound was performed to detect the presence of underlying postoperative DVT. Postoperatively patients were assessed for potential risk factors associated with higher incidence of DVT. Results: For the final analysis, 344 patients were included among them majority were males (n = 219, 63.66%) with overall mean age and SD was 47.52±12.02 years. The most common cause of fracture was road traffic accident (n = 178, 51.74%). The overall incidence of post-operative DVT Original Research Article Qureshi etal.; JPRI, 33(38A): 329-334, 2021; Article no.JPRI.70136 330 observed in our study was 9.30% (n = 32). Mean age 40.19±6.10 years, increased mean duration of operation 3.01±.078 hours, increased mean duration of post-hospitalization 18.49±7.37 days, raised mean WBC counts 20.12±5.64, and increased mean D-dimer levels 3.24±3.09 (laboratory cut off value 0.5mg/L) were significantly associated with higher incidence of DVT in patients operated for tibial plateau fractures. Conclusion: This prospective analysis has identified the potential modifiable risk factors associated with DVT. Consideration should be given to the preventable and treatable risk factors to prevent from the DVT associated complications.


INTRODUCTION
Following surgery of lower limb, deep venous thrombosis (DVT) could be the potential reason of pulmonary embolism and associated morbidity and mortality in hospitalized patients especially in patients with trauma. The overall incidence of tibial shaft fracture, 16.9/1000,000/years, tibial diaphyseal fracture accounts for 40%, and tibial plateau fractures accounts for 1-2% of all adult fractures and almost 32% of periknee fractures [1][2][3][4].
After the trauma, certain pathophysiological changes occur which causes hypercoagulation state, systemic inflammatory response, and trauma stress are the major risk factors leads to the development of DVT [5,6]. The risk of DVT further increased when extremity gets elevated after surgical procedure to reduce the mobility. In a study, Knudson et al., [7] proposed risk factors associated with venous thromboembolism particularly in patients with lower extremity fractures using the National Data Trauma Bank (NTDB) using a scoring system called Abbreviated Injury Score (AIS) of more than 3. Another author Shibuya with his colleagues [8] also used the NTDB for determining the incidence of DVT and pulmonary embolism (PE) in patients with fractures only affected foot or ankle and found the incidence rate of 0.28% and 0.21%, respectively. The overall incidence of DVT after tibial fracture is extremely low (6%) hence chemical prophylaxis for routine use is doubtful [9].
Post-surgical DVT prevention is purely dependant of underlying risk factors. By far, most of the previously conducted studies are focused on knee and hip joint arthroplasties, a specific population particularly old age group and patients who are immobilized for prolonged period. Epidemiological studies focusing on tibial plateau fracture is still lacking. Junyong Li and colleagues [9] have conducted a study but it does not cover the population residing at our region and also their advance health care facilities may be the reason of comparatively low incidence of DVT in their population and incidence of DVT might be high in our area. However, there is no any national database available through which the incidence of DVT can be documented that is why our study will fill the scientific gap present in our area.

Inclusion and Exclusion Criteria
Data collection was started after patients meet the following inclusion criteria: age more than 16 years and less than 60 years (as the chances of DVT increases after the age of 60 years due to comorbid conditions such as lack of mobility, CVA, or diabetes mellitus), undergoing surgery of tibial plateau fracture, and with no previous history of any type of lower limb surgery. Patients with metastatic fracture or having fracture of more than 4 weeks, concurrent fractures in other locations, patients with known coagulopathy, prehospitalization or preoperative presence of DVT, patients on anticoagulation were excluded from the study.

Methodology
As per the recommended management, all the patients with tibial plateau fracture were managed as per the protocol and treatment started with placement of inflatable tourniquet of affected limb after that subcutaneously Low molecular weight heparin (LMWH) with dose strength of 2500-4100IU was administered once daily in all admitted patients along with elevation of extremity of affected limb. Prevention of DVT was also followed postoperatively with LMWH and elevation of limb when diagnosed using Doppler ultrasound.
Tibial plateau fracture was diagnosed based on the history, presentation, clinical examination and confirmed on the basis of radiographic findings suggestive of tibial plateau fracture. A gold standard treatment, open reduction and internal fixation ((ORIF) was performed on all these patients. The diagnosis of DVT was made in accordance with the Guideline for the Diagnosis and Treatment of Deep Vein Thrombosis (3 rd edition), proposed by the Chinese medical association.
Patients were followed postoperatively for the development of DVT. Duplex ultrasonography (DUS) was performed on day one and on alternate days till discharge of patients. After the diagnosis, presence of DVT was categorized into two groups, proximal DVT (DVT localized in popliteal vein or proximally and/or presence of DVT proximally and distally) and distal DVT (distal to popliteal vein).

Data Collection and Analysis
Data were collected for demographic characteristics (age, gender, and area of residence), comorbidities (hypertension, diabetes mellitus, chronic liver or kidney disease), trauma (type of fracture either it was closed or open, and etiology of trauma), operative details like postoperative duration of hospital stay, and laboratory parameters (random blood sugar, hemoglobin levels, lactate dehydrogenase (LDH), white blood cell count (WBC), platelets count, and D-dimer level). Independent t-test and chi-square test were applied to determine the risk factors associated with DVT and a p value <0.05 was considered as statistically significant.

RESULTS
For the final analysis of patients, 344 patients were included among them majority were males (n = 219, 63.66%) and 36.33% (n = 125) were females with overall mean age and SD was 47.52±12.02 years. The age range was 16 years to 60 years with median age was 40.0 years. Majority of the patients operated were belongs to urban area as compared to rural, 58.7% (n = 202) and 41.27% (n = 142), respectively.
The overall incidence of post-operative DVT observed in our study was 9.30% (n = 32). Chart No. 01. Most commonly DVT observed in distal vein (n = 19, 59.37%) while DVT involved in proximal vein in 13 patients (40.62%) with an incidence rate of 1.9% and 1.3%, respectively.
Variables like mean age 40.19±6.10 years, increased mean duration of operation 3.01±0.78 hours, increased mean duration of posthospitalization 18.49±7.37 days, raised mean WBC counts 20.12±5.64, presence of diabetes mellitus, and increased mean D-dimer levels 3.24±3.09 (laboratory cut off value 0.5mg/L) were significantly associated with higher incidence of DVT in patients operated for tibial plateau fractures. Chart No. 01.

DISCUSSION
Tibial plateau fracture is rare and associated with low complication rate but occurrence of deep venous thrombosis in these patients although is not common but may sometime poses management challenge on clinicians and DVT associated complications like pulmonary embolism despite surgical treatment. The overall burden of tibial plateau fracture is less than 1% of all fractures and 8% of fractures occurring in elder population [10]. In our study, the overall incidence of post-operative DVT observed was 9.30%. A study conducted by Abelseth G and colleagues have observed the incidence of clinically occult DVT was 28%, of the represented fractures, 40% were of the femoral shaft (eight of 20), 43% of the tibial plateau (12 of 28), 22% of the tibial shaft (12 of 54), and 12.5% of the tibial plateau (one of eight) [11]. Another study conducted in china has shown quite higher incidence of DVT (46.43%) in postoperative patients with tibial plateau fractures [10]. The most common and logical reason behind this difference is could be due to their increased age causing higher incidence of DVT in patients operated for tibial plateau fracture as compared   Secondly, the reason of quite high incidence of DVT among these patients could be due to their selection criteria in which they have enrolled patients with underlying malignancies which we did not. Another possible reason could be the difference in mechanism of injury, the most common cause of tibial plateau fracture in our study was RTA while in their study it was high energy trauma with comparatively along with raised d-dimer levels as compare to our study. It is well established that high energy trauma is associated with systemic body stress response which results in a hypercoagulable state and also causes intimal damage and leads to the development of DVT.
In our study, more than 50% of the tibial plateau fractured occurred due to road traffic accident because tibial plateau fracture usually occurs due to high-energy trauma. Our findings are in favor with the previously conducted studies [12][13][14]. On the other hands, there are certain factors which contribute significantly for the development and higher incidence of DVT. In our study increased age more than 40.19±6.10 years, increased mean duration of operation 3.01±0.78 hours, increased mean duration of posthospitalization 18.49±7.37 days, raised mean WBC counts 20.12±5.64, and increased mean ddimer levels 3.24±3.09 (laboratory cut off value 0.5mg/L) were significantly associated with higher incidence of DVT in patients operated for tibial plateau fractures. Increasing age is a significant risk factor for the development of DVT in a study conducted by Auer R and colleague [15] age and increased D-dimer levels are also shown significant risk factor in a study conducted by Junyong Li [9]. There are certain studies that have shown delay in intervention is also associated with increased incidence of DVT [16,17] which we were unable to study.
Besides we tried to included most of the variables that are associated with increased risk of DVT but due to lack of resources and followup we were unable to included those such as assessment of immobilization of injured extremity pre and post intervention, presence of underlying malignancy, use of oral contraceptive pills in women, use of blood thinners, and transfusion of blood after the injury. Future studies needs to be focused on such areas so that these potential risk factors can be indentified and managed accordingly.

CONCLUSION
The incidence of DVT in our study is although not higher than other studies but the potential complications associated with DVT may put the patients into threatening situation and may be challenging to deal. The risk factors which we have identified through this study may also be associated with increased postoperative hospitalization, postoperative morbidity, and mortality.

CONSENT AND ETHICAL APPROVAL
Before commencement of study, hospital ethical review committee has approved the protocol and informed consent was taken from all patients before collection of data.