FEATURES OF THROMBOEMBOLIC COMPLIATIONS AFTER KNEE JOINT REPLACEMENT Vlasova I.V., Vlasov S.V., Milyukov A.Yu., Tsuryupa V.N
Regional Clinical Center of Miners’ Health Protection, Leninsk-Kuznetsky, Russia
One of the main tasks in orthopedics and traumatology is treatment of diseases and damages of big joints, with knee osteoarthrosis deformans, which consists almost a quarter of them (24.7 %). It causes the primary disability in 31.2 % of all pathologic states of the locomotor system [1, 2]. Endoprosthesis replacement is a highly efficient technique normalizing the function of an injured joint and correcting the pain syndrome [1].
As any extensive orthopedic surgery, knee joint replacement (KJR) can cause some complications [3]. Deep venous thrombosis (DVT) is one of them. High invasiveness of the intervention, blood loss, use of bone cement, and high comorbidity according to data of the normogram and ASA (the classification of the objective status of American Society of Anesthesiologists) are the promoting factors of clot formation. Besides, the features of a surgical intervention, i.e. forced attitude of the extremity during surgery (flexion), results in temporary disorder of venous outflow from the extremity. All above-mentioned factors determine the high risk of DVT in KJR, which 1.5-2 times higher than the risk in hip replacement [4].
The rate of thrombotic complications of KJR is quite variable in various clinics, and varies within 9-64 % according to the studies. Thromboembolic complications worsen the treatment outcomes, lengthen the hospital stay, increase the financial costs and can cause pulmonary embolism [1-5]. The use of various measures for prevention is directed to decrease in complications [3-7]. Therefore, the problem of timely and qualitative diagnostics of DVT in patients after KJR is important.
Ultrasonic duplex scanning (DS) with color doppler mapping is widely used in clinics [8-12]. Sensitivity and specificity of the technique for diagnosis of proximal thrombosis is high and reaches 98-100 %. The deep veins of the leg are difficult to examine. The sensitivity of DS in identification of venous thrombosis of the leg varies from 60 to 90 % according to various data.
The difficulties of examination of the veins of the leg are mainly determined by their anatomical features. Deep veins of the leg are the paired posterior tibial veins (PTV) and the anterior tibial veins (ATV) (which form the popliteal vein), fibular veins (FV) and sural veins. The number of the veins varies from 2 to 4 around the same-name artery. Also the system of anastomoses of all veins of the leg and between the superficial and deep venous network is quite developed and variable. Sural veins (SV) present the high interest too. They are the muscular venous sinuses in the thickness of sural and soleus muscles, which play the important role in pathogenesis of chronic venous insufficiency [13, 14]. The diameter of SV is quite variable: from big (> 1 cm) to small (Fig. 1). However proper scanning in various planes with use of color and energetic mapping, and B-flow mode allow achieving the visualization of the veins of the leg in approximately 90 % of cases [15].
Figure 1
Muscular venous sinuses of the leg in longitudinal and transverse scanning of gastrocnemius muscle.
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The objective of the study was identification of the features of the thrombotic process and the protocol for examining the patients after total KJR.
MATERIALS AND METHODS
The examination included 570 patients after total knee joint replacement in 2014-2017 in the Regional Clinical Center of Miners’ Health Protection. There were 442 women and 128 men. The mean age was 64 (47-79).
The study was conducted according to World Medical Association Declaration of Helsinki – Ethical Principles for Medical Research Involving Human Subjects, 2013, and the Rules for clinical practice in the Russian Federation (the Order by the Russian Health Ministry, June 19, 2003) with the written consent for participation in the study and approval from the local ethical committee of the center (the protocol No.3, February 15, 2018). Low molecular weight heparin (fraxiparine, 0.3 mg/day, clexane, 0.2 mg/day) was prescribed for prevention of thrombotic complications for all patients 10-12 hours after surgery. Aspirin and trental were used from the second day. Non-specific prevention included the use of compression knitwear. The physical rehabilitation with remedial gymnastics and early activation of the patients were conducted. Warfarin was prescribed with the dosage of 5 mg/day.
DS of magistral vessels of the lower extremities was conducted with the expert ultrasonic system MyLab Class (Esaote, Italy). For exclusion of the thrombotic process, the examination was conducted before the surgery and on the days 2-3 after KJR. If any thrombotic complications were found, the examination was repeated each 2-3 days.
The patients were examined in horizontal supine position. Considering the impossibility of changing the position, the popliteal veins were examined with slight flexion of the extremity in the knee joint and abduction of the extremity to the outside. The major problems appeared in scanning of the veins of the leg. During the first day after surgery, all patients demonstrated the evident edema of soft tissues in the periarticular region and in the leg. In some cases, edema compressed the veins and caused the impossibility of their visualization. Besides, many patients (mainly, the women) had the excessive body weight. Thick subcutaneous fat tissue in the legs impeded the visualization too.
The techniques promoting the venous visualization were used for negotiating these problems. The extremity was positioned with support to the foot (or the heel) with slight flexion in the knee joint. At that, the maximal relaxation of the leg muscles was achieved. In this position, the proper transverse sliding scanning with use of intensive compression with the transducer for each centimeter of sliding was carried out. The transducer was moved from the popliteal region downwards along the posteriomedial or posteriolateral surface of the leg. The medial and lateral sural veins and proximal PTV were visualized. Then proper scanning along the medial surface from the ankle joint to the popliteal region was conducted. Therefore, PTV and SV were examined in the muscles at the level of the middle and upper one-third. FV were visualized with this approach in some patients, but FV compression could not be full in all cases due to high deepness of the muscles. For this reason, the study with color mapping did not lead to full staining of the veins, resulting in a possibility of a false positive result. Therefore, the examination of FV was repeated from the lateral approach. The best visualization of FV was achieved in transverse scanning along the lateral surface of the leg at the level of the middle one-third. During the compression tests, it was efficient to use the back pressure by the hand to the leg muscles from the opposite site. The final decision on venous patency was made on the basis of transverse scanning, when the venous lumen and a degree of its compression were evident.
The strict adherence to the algorithm gives the satisfactory visualization of all veins of the leg in most cases.
RESULTS
The thrombotic complications were identified in 103 patients (18 %) (the table).
Table
Distribution of patients according to location of venous thrombosis
| Incidence of thrombosis |
Amount of patients |
% |
| All leg veins and popliteal vein | 4 | 3.9 |
| Posterior tibial, fibular and sural veins | 6 | 5.8 |
| Posterior tibial and sural veins | 10 | 9.7 |
| Posterior tibial and fibular veins | 2 | 0.3 |
| Posterior tibial veins | 24 | 23.3 |
| Isolated thrombosis of sural veins | 57 | 55 |
The thrombotic process was limited by the veins of the leg in almost all cases. Thrombosis extended to the popliteal veins in 4 cases only. The thrombotic process was extensive, with affection of PTV, FV and SV, in 6 patients (Fig. 2).
Figure 2
Occlusive masses in fibular veins in extensive thrombosis of leg veins.
Therefore, DVT with significant disorder of outflow from the leg was found in only 9.7 % of all thrombosis (10 patients).
DVT was not extensive in all other cases. In thrombosis of only PTV (24 patients) and in combination of thrombosis of PTV and SV (10 patients), the feature was a lesion of one of the paired veins or non-occlusive pattern of the process. The veins were often clotted in the middle and proximal one-third of the leg with normal patency in the distal one-third. Satisfactory outflow was from the leg in the paired patent veins and in the anastomoses with other veins of the leg.
A half of all cases of DVT included thrombosis of only muscular venous sinuses. DS showed some hypoechogenous or isoechoic spindle-shaped structures, with absence of compression, without blood flow inside or with weak parietal flow in distal compression. The thrombotic process was limited by sinuses, without extension to SV entries (Fig. 3).
Figure 3
Occlusive thrombosis of sural veins.
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SV thrombosis was without any clinical manifestations, and without pain in compression by the transducer during the examination.
Active anticoagulant therapy was prescribed (fraxiparine, 0.6-0.9 mg/day, clexane, 0.4 mg/day) with shift to warfarin (5 mg) and achievement of the targeted value of INR of 2-3, with continuation of therapy up to 3-6 months at the outhospital stage. The compression knit-wear was used.
Over the time, DS did not show any progression of the process in any cases. Some signs of repatency were identified by the end of the week in all cases of thrombosis of PTV and FV. The blood flow in the distal part of the leg in the region of perforants recovered with the highest rate.
The time course in isolated thrombosis of SV showed two variants. In most cases, the vein decreased in the diameter due to retraction of a clot, but the occlusive process was persistent during the whole period of hospital stay. In rare cases, the process of repatency in view of slight parietal blood flow appeared in distal compression of the leg (Fig. 4).
Figure 4
Initiation of recanalization in sural veins.
The dynamic observation was continued after hospital discharge. DS was repeated one month later. Ascendant thrombosis was not identified in any cases. The process of repatency in PTV and FV was active. Some residual events such as incomplete compression of the vein and valvular insufficiency were found. Venous obliteration happened in SV thrombosis. One month later, it was impossible to differentiate the vein from the surrounding tissue in most cases.
DISCUSSION
KJR is associated with high risk of thrombotic complications. DVT was identified in 18 % of the operated patients. Despite of the limited amount of cases of DVT, 90 % of the cases had the limited pattern. A half of cases of thrombosis located in only muscular venous sinuses, without distribution to the magistral veins. SV thrombosis can be the beginning of extensive thrombotic process that we could observe on the regular basis, for example in critically ill patients with polytrauma and long term immobilization. Therefore, it is not acceptable to ignore these measurements despite of their local pattern.
Timely therapy after identification of the thrombotic process resulted in active venous recanalization, without cases of progression of the complication.
The outflow from SV highly depends on normal activity of the muscular-venous pump. The velocity of blood though SV is very slow at rest, and the possibility of stasis with clot formation is high. Long term intrasurgical flexion of the extremity disorders the venous outflow, and SV are most vulnerable. It explains the fact of lesion of SV in 77 of 103 (74.7 %) cases.
Monitoring of thrombotic complications in extensive orthopedic operations is common during almost 20 years in our clinic. The analysis of complications in 2008-2009 has shown the high rate of venous thrombosis in the lower extremities. It resulted in necessity of analyzing the causes. The arresting bleeding tourniquet for prevention of intrasurgical blood loss was shown as one of the provoking factors of clotting in KJR. Refusal from the tourniquet and the decrease in time of surgery decreased the amount of thrombotic complications from 19 to 9.5 % [11]. However the protocol of the ultrasonic examination included only the magistral veins of the leg (PTV, ATV, FV). The accumulated experience and the use of high resolution ultrasonic scanners caused the revision and clarification of the examination volume. Obligatory examination of all veins, which are available for visualization (including muscular venous sinuses resulted in almost two-fold increase in the rate of thrombotic complications as compared to achieved 9.5 %, but determined the true picture of postsurgical condition of the venous system [16].
Ultrasonic diagnosis specialists often do not conduct the full volume of examination of the veins of the leg. It is associated with difficulty of identification of all deep veins that is determined by various variants of connection and significant increase in time of estimation. The studies showed that DS protocol for estimation of muscular and fibular veins could decrease the amount of false-negative outcomes in DVT by 64 and 15 % correspondingly [8, 16].
CONCLUSION
1. Thrombotic complications in KJR were identified in 18 % of cases. A half of the cases were local thrombosis of muscular venous sinuses of the leg that were possibly associated with specific position of the extremity during surgery, resulting in temporary disorder of venous outflow from the leg.
2. The feature of thrombotic complications of KJR is the process limited by the veins of the leg, non-severe pattern of thrombosis, preservation of sufficient outflow from the leg through passable paired veins in most cases, active recanalization of the veins in timely therapy.
3. The examination protocol with duplex scanning for patients after KJR should include the examination of muscular venous sinuses and fibular veins.
Information about financing and conflict of interests
The study was conducted without sponsorship.
The authors declare the absence clear and potential conflicts of interests relating to publication of this article.