In the prevention of thromboembolic disease associated with joint replacement, our goal is to avoid fatal pulmonary embolism while reducing the incidence of deep vein thrombosis and its associated complications, such as post-thrombotic syndrome, pulmonary hypertension, and recurrent deep vein thrombosis. There are still a few controversial topics in the field of orthopedics, and the same is true for the prevention of thromboembolic disease. Prevention must be done, that is the more unified view, and the outstanding question is how to choose the type and timing of pharmacological prophylaxis.
Prevention
Routine prophylaxis refers to a set of preventive measures that begins with the patient’s choice of anesthesia and includes pharmacologic prophylaxis, mechanical device prophylaxis, and routine monitoring for DVT.
Anesthesia
The use of lumbar or epidural anesthesia has been shown to reduce the incidence of postoperative DVT by 40% to 50% independent of pharmacologic prophylaxis, and the reasons for this appear to be mainly related to improved blood flow to the lower extremities during and after surgery. However, the use of such anesthesia should take into account the incidence of epidural hematoma and the effect of the combined application of low molecular weight heparin. Epidural or intradural manipulation should be avoided for 12 hours before and after the administration of a single dose of LMWH.
Pharmacological prophylaxis
Postoperative pharmacological prophylaxis can be administered in a variety of ways, including warfarin, heparin, aspirin, dextran, and a number of newly developed drugs.
Studies have demonstrated that aspirin reduces mortality by approximately 60% in patients with unstable angina and 25% in patients with cerebrovascular events, while prevention of venous system thrombosis has not been as definitive. Despite the questionable improvement in the incidence of PE and DVT, many people are still using low-dose aspirin for prophylaxis.
The use of warfarin for pharmacological prophylaxis. The incidence of fatal PE decreased from 3.4% to 0.05% after low-dose warfarin prophylaxis from the fifth postoperative day in the study. Subsequently, Amstutz reported a non-fatal PE rate of 0.065% with no associated deaths following the postoperative warfarin prophylaxis regimen. However, there were some serious bleeding complications that required reoperation. The incidence of hemorrhagic complications was approximately 12% at the beginning of the study and was reduced to approximately 1.5% after downward adjustment of the warfarin dose, while the incidence of minor hemorrhagic complications, such as hematomas that did not require further surgical management, ranged from 3.2% to 12%.
Heparin fragments, or LMWH, have the advantage of eliminating the need to monitor coagulation and reducing the risk of heparin-induced thrombocytopenia. LMWH is more active and has an earlier onset of action during the coagulation cascade than regular heparin. LMWH has been found to reduce the risk of thrombocytopenia to 8-15%, and is therefore more effective than warfarin in reducing the risk of DVT.
However, the incidence of bleeding events associated with LMWH was approximately six times higher than in the control group, with a 50% increased risk compared to the warfarin group, particularly in patients with renal disease, advanced age, and women. This paradox of reducing the incidence of DVT at the cost of hemorrhagic complications has sparked widespread controversy among many surgeons and internists.
Mechanical prophylaxis
Mechanical thromboprophylaxis techniques include not only the intraoperative and postoperative application of intermittent pneumatic compression compression stockings, but are also related to the technique and timing of the procedure as well as the rehabilitation activity program developed by each surgeon after surgery.
Mechanical compression devices for the lower leg allow an increase in blood flow and thus improve intra- and postoperative hypercoagulability of the venous system, without increasing the risk of bleeding and without requiring special monitoring techniques.
The benefits of using mechanical prophylactic devices in addition to conventional pharmacological prophylaxis are significant and the risk is negligible. Death is caused by the surgical operation itself. This suggests that deaths that may occur at any time are simply caused by surgical trauma. The risk from prophylaxis is likely to exceed the risk from fatal PE. Due to the extremely low number of cases of fatal PE, large clinical trials are necessary to analyze whether the use of pharmacological prophylaxis leads to any difference7.
There is insufficient evidence as to whether the use of modern pharmacological prophylaxis techniques to reduce the incidence of DVT leads to a statistically proven downward trend in the incidence of fatal PE.
Dangers of pharmacological prophylaxis
The risk of serious hemorrhagic events during the use of pharmacologic prophylaxis is of concern and needs to be weighed against the risks of fatal PE, nonfatal PE, and DVT. As previously mentioned, the expected risk of death from PE, without considering the effect of the prophylaxis method, is currently stable between 0.01% and 0.02%. We also note that the use of enoxaparin significantly increases the risk of bleeding to approximately 5% compared to 2.3% with the warfarin regimen.
Therefore, there is a real need to adjust and balance the reduction of the DVT rate and its secondary post-thrombotic syndrome and pain complications with the increased incidence of bleeding complications. It is important to note that under modern surgical and postoperative rehabilitation techniques the mortality rate of PE is stable between 0.01% and 0.02% and is not significantly associated with prophylactic methods.
So where do we go from here?
Each patient should be evaluated preoperatively regarding his or her risk factors. Patients will be asked to complete the following things prior to surgery: stop hormone replacement therapy one month prior to surgery, stop smoking, and stop antiplatelet medication two weeks prior to surgery. It is recommended that 40 mg of LMWH be given 12 hours prior to surgery (except in cases of severe renal insufficiency). Intraoperative local anesthesia is preferred, but this makes it difficult to administer LMWH preoperatively, and the duration of the procedure should be kept as short as possible and intraoperative calf compression stockings should be used for the contralateral leg. Special LMWH may be considered for elderly patients, women, and patients with chronic renal insufficiency, and the dose of LMWH should be reduced. If the patient’s creatinine clearance is too low, perhaps a low dose of warfarin can be considered as a substitute for LMWH.
All patients should begin an early activity and rehabilitation program, including deep breathing and seating out of bed. Patients can begin weight-bearing activities on the first postoperative day if conditions permit. Doppler ultrasound screening for thrombus is performed on the fifth postoperative day, and oral aspirin 150 mg daily for six weeks after discharge. Some studies have demonstrated that this regimen reduces the incidence of cardiovascular and cerebrovascular events in the postoperative phase. Doppler ultrasound should be repeated if associated clinical symptoms develop. Patients with high-risk factors should be started on warfarin prophylaxis with a goal of an internationally standardized rate of less than 2.
If a patient presents with asymptomatic non-occlusive calf vein DVT, LMWH should be continued until six weeks postoperatively. In contrast, if occlusive DVT is found, warfarin therapy should be used with an INR control between 2 and 2.5. Patients with confirmed pulmonary embolism should be started on a warfarin regimen with an INR control goal between 2 and 2.5. Clinical awareness should be provided to these patients until 6 to 12 weeks postoperatively.
In conclusion, the mortality rate of PE after major orthopedic surgery has remained between 0.01 and 0.02% under conditions using modern surgical techniques, and modern pharmacological prophylaxis methods have not significantly altered this level. Mechanical prophylaxis can reduce the incidence of DVT without increasing the incidence of hemorrhagic complications. Modern pharmacological prophylaxis can also reduce the incidence of DVT. However, they can also significantly increase the risk of hemorrhagic complications. It has not been demonstrated that the benefit of reduced DVT risk in patients can compensate for the increased risk of hemorrhagic complications.