Preventing VTE in Below-the-Knee Surgery
Venous thromboembolism (VTE) following hip fractures and hip/knee arthroplasty—both deep vein thrombosis (DVT) and pulmonary embolism (PE)—has been relatively well studied. We therefore have a fairly clear understanding what the risks for DVT and PE are with no treatment as well as with modern preventive chemotherapeutic agents. However, such clarity on the need for and effectiveness of VTE prophylaxis is lacking for below-the-knee (BTK) orthopaedic procedures. This is largely due to the fact that such procedures have been deemed “low risk”—despite a dearth of supporting evidence for that assumption. In the March 20, 2019 issue of The Journal, Heijboer et al. used a sophisticated propensity score matching methodology to evaluate the rate of VTE in >10,000 BTK surgery patients at their tertiary care referral center.
The authors evaluated patients who underwent orthopaedic surgery distal to the proximal tibial articular surface, including foot/ankle procedures, open reduction of lower-leg fractures, and BTK amputations. They performed propensity score matching to compare 5,286 patients who received any type of chemotherapeutic prophylaxis with the same number who did not, across several key risk categories. The good news is that VTE prophylaxis effectively lowered the risk of symptomatic DVT or PE from 1.9% to 0.7% (odds ratio of 0.38, p <0.001).
Unfortunately (but not surprisingly), this effectiveness came at the price of increased systemic or local bleeding among patients using chemical VTE prophylaxis, with an incidence of 1.0% in the no-prophylaxis group and 2.2% in the prophylaxis group (odds ratio of 2.18, p <0.001). The authors did not assess the incidence of deep infection or hematoma formation, which often accompany increased local bleeding. The low overall incidence of VTE and bleeding did not allow for subgroup analysis according to location of surgery, and aspirin use was not controlled for in their study. In addition, Heijboer et al. used hospital coding data, and the accuracy of the database was not assessed.
The authors recommend that “anticoagulant prophylaxis be reserved only for patient groups who are deemed to be at high risk for VTE,” but we still don’t know precisely who is at high risk among BTK surgery patients. It is my hope that these findings will prompt large, prospective multicenter trials in the foot and ankle community to better determine which types of patients should be exposed to an increased risk of postoperative bleeding complications in order to achieve a clinically important decreased risk of VTE with chemical prophylaxis.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
Tranexamic Acid: Effective—and Safe—in THA
Prior research has established that total hip arthroplasty (THA), in and of itself, is associated with a small increased risk of venous thromboembolism (VTE). Hence the concern that routinely administering the antifibrinolytic drug tranexamic acid (TXA) perioperatively, as is commonly done nowadays to reduce blood loss during surgery, might further increase the risk of THA-related thromboembolic events. But the findings from a large population-based cohort study by Dastrup et al. in the October 17, 2018 JBJS, should allay many of those concerns.
The authors evaluated >45,000 Danish patients who had a THA between 2006 and 2013. Approximately 85% of those patients received intravenous TXA perioperatively, while the rest did not. Dastrup et al. evaluated adverse cardiovascular events (VTE, deep venous thrombosis, pulmonary embolism, myocardial infarction, and ischemic stroke) among those patients over 30 postoperative days, and they found no increased risk in any of those outcomes among the patients who received TXA relative to those who did not. These optimistic findings were essentially the same when the authors analyzed the data using a multivariable model and with propensity-score matching.
Dastrup et al. conclude that TXA in the setting of THA is safe with respect to VTE, and David Ayers, MD, commenting on the study, concurs. However, Dr. Ayers cautions that the study did not have the statistical strength to evaluate the potential cardiovascular risks of TXA in THA patients who have undergone previous cardiac procedures, such as stent placement. He therefore suggests that “further safety evaluation should be directed toward [such] patients at higher risk for complications after receiving TXA.”
JBJS Editor’s Choice—VTE Risk with Metastatic Skeletal Lesions: Fix Prophylactically or Not?
In the February 15, 2017 issue of The Journal, Aneja et al. utilize a large administrative database to examine the critical question of venous thromboembolism (VTE) risk as it relates to managing patients with metastatic femoral lesions. The authors found that prophylactic intramedullary (IM) nailing clearly resulted in a higher risk of both pulmonary embolism and deep-vein thrombosis, relative to IM nailing after a pathologic fracture. Conversely, the study found that patients managed with fixation after a pathological fracture had greater need for blood transfusions, higher rates of postoperative urinary tract infections, and a decreased likelihood of being discharged to home.
The VTE findings make complete clinical sense, because when we ream an intact bone, the highly pressurized medullary canal forces coagulation factors into the peripheral circulation. When we ream after a fracture, the pressures are much lower, and neither the coagulation factors nor components of the metastatic lesion are forced into the peripheral circulation as efficiently, although some may partially escape through the fracture site.
One might conclude that we should never consider prophylactic fixation in the case of metastatic disease in long bones, but that would not be a patient-centric position to hold. In my opinion, the decision about whether to prophylactically internally fix an impending pathologic fracture should be based on patient symptoms and consultations with the patient’s oncologist and radiation therapist.
If all of the findings from Aneja et al. are considered, and if the patient’s symptoms are functionally limiting after initiation of appropriate radiation and chemotherapy, prophylactic fixation should be performed, along with vigilantly managed VTE-prevention measures. This study is ideally suited to inform these discussions for optimum patient care.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
FDA Approves Pradaxa for Thromboprevention After Hip Replacement
The FDA this week approved dabigatran (Pradaxa) for prevention of DVT and pulmonary embolism following hip arthroplasty surgery. The approval follows FDA analysis of two randomized phase 3 trials (RE-NOVATE and RE-NOVATE II) in which patients who took dabigatran experienced lower rates of venous thromboembolism and all-cause death than those who took enoxaparin. Conversely, those taking the higher dose of dabigatran (220 mg) had higher rates of major bleeding than those taking enoxaparin.
The FDA initially approved dabigatran to reduce the risk of stroke and embolism in patients with nonvalvular atrial fibrillation; the recent hip-replacement indication is the fourth in five years for this novel anticoagulant.
Perhaps most significantly for orthopaedists who now might prescribe dabigatran for hip-replacement patients, last month the FDA approved the first drug (idarucizumab, or Praxbind) to reverse the effects of dabigatran, possibly making the higher risk of bleeding with dabigatran less of a clinical concern.
Aspirin’s Effectiveness in VTE Prevention Varies by Procedure
“Deep vein thrombosis of the right leg” by James Heilman, MD – Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons
A recent meta-analysis of eight randomized trials (1,408 total patients) compared aspirin to anticoagulants such as warfarin and dabigatran for preventing venous thromboembolism (VTE) after hip and knee arthroplasty and hip-fracture repair. The analysis found that the overall prophylactic power of these two medical approaches was essentially equal following major lower-extremity surgery. However, the comparison, appearing in the Journal of Hospital Medicine, found a slightly higher (but statistically nonsignificant) risk of deep vein thrombosis (DVT) with aspirin following hip-fracture repair. Conversely, the risk of bleeding after hip-fracture surgery was lower with aspirin than with anticoagulants.
For additional insight into VTE prophylaxis, view the FREE recorded JBJS webinar “Preventing Arthroplasty-Associated Venous Thromboembolism.” Register here.
Thromboprophylaxis Unwarranted After Lower-Leg Fractures
The venographic prevalence of deep vein thrombosis in people with distal lower-extremity injuries that require surgery or casting ranges from 10% to 40%. But a prospective cohort study in the May 21, 2014 JBJS found that only 0.6% of 1200 patients with lower-leg fractures and no medical or mechanical thromboprophylaxis had symptomatic, objectively confirmed venous thromboembolism (VTE) over a 12-week follow-up. Moreover, none of the seven thrombotic complications was fatal. This leads the authors to conclude that “the risk-benefit ratio and cost effectiveness of routine anticoagulant prophylaxis are unlikely to be favorable for these patients.” They go on to say that despite the large sample size in this study, the low prevalence of VTE made it impossible to pinpoint characteristics that could identify a subgroup of similar patients who might be at higher risk of clotting problems.
AAOS Annual Meeting Roundup
With 840 scientific presentations, 560 posters, and 200 instructional course lectures, even OrthoBuzz couldn’t comprehensively summarize the 2014 AAOS Annual Meeting in New Orleans. But here’s a small random sampling of findings reported at the meeting that you might find interesting. Please remember that these data have not appeared in peer-reviewed journals and should be considered preliminary.
TENS for Low Back Pain Could Save Medicare Nearly a Half-Billion Dollars
If all of its estimated 1.5 million beneficiaries with chronic low back pain were treated with TENS—transcutaneous electrical nerve stimulation—Medicare could save about $417 million in annual treatment costs, said Michael Minshall, MPH (paper #474). The figures are based partly on published research showing that TENS patients use significantly fewer health care resources (hospital and office visits, imaging, physical therapy, and surgery) than those receiving other treatments.
Allografts Fail Three Times More Frequently than Autografts in Primary ACL Reconstruction
A prospective randomized trial of 99 ACL reconstruction patients in their twenties revealed a 10-year 26.5% failure rate when tibialis posterior tendon allografts were used, compared with an 8.5% failure rate for hamstring autografts. Presenter Craig Bottoni, MD (paper # 462) said both groups received the same fixation technique and the same postoperative rehab program by physical therapists who were blinded to the treatment allocation.
Tranexamic Acid Cuts Transfusion Rates during TJA without Boosting VTEs
Scott Wingerter, MD (paper #1) presented data from Washington University School of Medicine (WUSM) showing that transfusion rates declined substantially during primary and revision hip and knee replacement procedures after tranexamic acid began being used routinely at WUSM. The incidence of venous thromboembolism was also lower in the group that received tranexamic acid, although that difference was not statistically significant.
Repeat Skin Antisepsis May Reduce Surgical Site Infections
A randomized, prospective study of nearly 600 patients undergoing total joint replacement found that those who received additional skin antisepsis with an iodine povacrylex/alcohol combination after surgical draping but before incise draping were far less likely to experience a superficial surgical site infection than those who received standard skin preparation with chlorhexidine, alcohol, and betadine. Presenter Tiffany Morrison, MS (paper # 49) also noted a non-significant difference in rates of skin blistering between the two groups.
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