Orthopedic & Muscular System: Current Research
Open Access

Using Heparin Aspirin Protocol for Venous Thromboembolism Prevention in Knee or Hip Arthroplasty

^*Correspondence: . Hassan Kassir, Bone and Joint Reconstruction Research Center, Shafa Orthopedic Hospital, Iran University of Medical Sciences, Tehran, Iran, Tel: + 989125524663, Email:

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Introduction

Background

Joint Arthroplasty is one of the most common orthopedic surgeries. Venous Thromboembolism (VTE) is a remarkable side effect of arthroplasty. In VTE a blood clot obstructs the vein system and it includes: Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE) [1]. The prevalence of vein thrombosis after joint arthroplasty without medical or physical prophylactic approaches is 40-80 percent. Pulmonary embolism mortality rate among these patients is about 2 percent and 10-20 percent of PEs are without significant symptoms [1-3]. Using anticoagulants decreases the risk of venous thrombosis up to 30 percent [4]. Common prophylactic anticoagulation approaches include:

• Low Weight Molecular Heparin (LWMH; such as Enoxaparin): It decreases risk of thrombosis about 65-93 percent, but it increases the risk of bleeding in surgical site [5].

• Oral Warfarin: It needs regular laboratory assessment and increases the risk of bleeding about 3-4 percent [6].

• Aspirin: It is a low risk, reliable and cost-effective alternative for other pharmaceutical approaches [7].

• Mechanical prophylaxis (compression stockings or intermittent pneumatic compression) [8].

Although most surgeons prescribe anticoagulants after arthroplasty, choosing the best method is controversial. Van Andrichen AM and his colleagues showed that low molecular weight Heparin can’t prevent the symptomatic thromboembolism after arthroscopic knee surgery [9]. Also prescribing aspirin is controversial. Gatouski CJ and his colleagues indicated that aspirin decreases the risk of arterial thromboembolism but increases the risk of VTE in a 90 days period after surgery [10].

In this study, we evaluate the effectiveness of heparin- aspirin prophylactic method in preventing VTE in our patients after total knee or hip arthroplasty and we compare it with the results of other methods in several studies.

Materials and Methods

This quasi-experimental interventional study has been conducted in patients who underwent Total Knee Arthroplasty or Total Hip Arthroplasty at Shafa Yahyaian Hospital between years 2019 and 2020. The inclusion criteria consisted of “age>18 years old” and “mild or moderate risk according to Caprini risk category” (Figure 1). The following were the exclusion criteria: The surgical site becoming infected which leads to reoperation, dismissing follow- up, having history of cardiovascular disease or thromboembolism and deducting high incidence risk of thromboembolism or being in the high risk group according to Caprini risk category.

Figure 1: Caprini risk factors and score risk category association. Note: BMI: Body Mass Index; COPD: Chronic Obstruction Pulmonary Disease; IBD: Inflammatory Bowel Disease; VTE: Venous Thromboembolism.

A physician observed patients regularly about extensive hematoma, surgical site infection, diffuse ecchymosis and bleeding. Patients received 5000 units of Heparin per 12 hours for 5 days and after the patients received Aspirin 80 mg tablets daily for one month. The duration of follow-up was 6 months after hospital discharge. The surgeon, method of surgery and the prosthesis were similar for all patients. All of them underwent spinal anesthesia. The post-operative care was similar for all patients (starting to walk 24 hours after surgery under supervision of a physiotherapist, starting active knee movement after 5 days and reaching to 90 degree flexion of knee before hospital discharge). If there had been any suspicion to thrombosis after surgery, the patient underwent Doppler ultrasonography.

Our data has been extracted from medical records of patients and after surgery the data has been documented by researcher or orthopedic residents with emphasis on side effects of surgery. At last we analyzed our data with the 24th edition of SPSS software. The quantitative variables have been presented as mean ± standard deviation and categorical variables have been presented as percentage. T test has been used for comparison between quantitative variables; for non-normal distribution, Mann- Whitney test has been used. The qualitative variables have been compared by Chi-squared test or Fisher’s exact test. The statistical significance and confidence interval have been considered 0/05 and 95%, respectively.

Researchers have respected the principles of Helsinki declaration and the regulations of Iran University of Medical Sciences Ethical Committee. All data are anonymous and informed consent have been gotten from all patients.

Results

During our study, 48 and 220 patients underwent Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA), respectively. From these numbers, 26 cases of THA and 133 cases of TKA analyzed in the study (Figure 2).

Figure 2: Enrollment in the study.

We evaluated several variables (Table 1). The number of female participants was 4 times more than male, although this proportion in THA was equal. The mean age of participants was 62.7 years and the mean age of TKA cases was about 20 years higher than THA cases. The mean of platelet cells count was significantly different before and 5 days after surgery in each group (P-value=0.0001 for both) but there we didn’t detect a significant difference between two groups. The mean body mass index was 28.59. We found a significant difference in number of smokers between THA and TKA groups (P-value=0.027).

Table 1: Demographic variables in Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA).

In TKA group, from 133 cases, 19 (14.28%) experienced the complications of surgery. 10 cases of ecchymosis, 6 cases of swelling and one case of embolism. The other 2 cases suffered from other complications which were irrelevant to VTE. In THA group, we didn’t find symptoms of VTE except one case of swelling which was normal in Doppler ultrasonography imaging.

Discussion

We found that aspirin-heparin protocol decreases the risk of Venous Thromboembolism after Total Knee or Hip Arthroplasty. The incidence rate of VTE after total knee arthroplasty without anticoagulation prophylaxis admission is about 40 to 84 percent; otherwise, by applying aspirin-heparin protocol the incidence rate of this complication in our TKA group was 0.75 percent.

Totally the sex ratio (male/female) was ¼ and the proportion of female to male patients in TKA group was even higher (male/ female=1/5), but in THA group the numbers of male and female patients were approximately equal. Perhaps it indicates that women need more TKA than men but the indication of THA is similar for men and women. The mean age of TKA cases was about 20 years higher than THA cases. This may show that old age is one of the main risk factors that leads to TKA but about THA other risk factors are more important. In both groups the mean of platelet cells count before and after surgery were different. It seems that it regards to bleeding during surgery. The mean of Body Mass Index (BMI) was 28.59, but this variable was significantly higher in TKA group (P=0.001). In other words, the BMI is a more important risk factor for indication of TKA than THA. Anderson DR and his colleagues compared the efficacy of rivaroxaban with aspirin in their study. The incidence rate of embolism in their aspirin consuming group was 0.64% which is approximately similar with the result of our study (0.62%) [11]. In another study at 2019, Warren JA. And his colleagues analyzed the data of 363530 patients who had undergone THA and/or TKA surgery from year 2008 to 2016. They found that on average 1 of 71(1.4%) patients who undergo TKA and 1 of 167 (0.5%) patients who undergo THA will experience VTE in a period of 30 days after surgery; while this proportion for TKA group in our study was 1 to 133 [12]. One of our limitations was small sample size. Some cases didn’t consent to participate in the study and some others discontinued their follow-up process after surgery. In addition, we just assessed patients which had clinical symptoms of Venous Thromboembolism. We didn’t assess our patients with venography or Doppler ultrasonography except in symptomatic cases. Thus we may miss the non-symptomatic cases of VTE. At last, confirmation of these results would require more studies with longer follow-up duration, bigger sample size and more accurate and precise laboratory and imaging evaluation.

Conclusion

The incidence rate of embolism and ecchymosis in this study was 0.62% and 6.2%, respectively and they are lower than similar studies. This shows that aspirin-heparin protocol is a good option for preventing Venous Thromboembolism after Total Knee Arthroplasty and/or Total Hip Arthroplasty.

Conflict of Interest

The authors declare that there are no conflicts of interest.

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