Routine administration may be unnecessary or even harmful

The risk of deep vein thrombosis (DVT) and pulmonary embolism (PE) and the appropriate measures to prevent these conditions continue to be subjects of research and discussion among orthopaedic surgeons. At the American Orthopaedic Foot & Ankle Society (AOFAS) 2011 Specialty Day, several surgeons provided information and perspectives on the issue.

Chemical thromboprophylaxis
Jamie T. Griffiths, MBBS, BSC, reported on a series of 1,625 patients in the United Kingdom over the period from 2003 to 2010. From 2003 through 2006 (555 patients), aspirin was used as chemical thromboprophylaxis after elective foot and ankle surgery. From 2007 onward (1,070 patients), no form of chemical thromboprophylaxis was used. All patients had mechanical measures of stockings and foot pumps.

A clinically significant thromboembolic event developed in only 5 patients in the entire group (0.31 percent) (Table 1). In 3 patients—each of whom was in the aspirin group—DVT developed at an average 5 weeks postoperatively. The other 2 patients had not received aspirin, and nonfatal pulmonary emboli developed at an average 7 weeks postoperatively.

Dr. Griffiths noted that an estimated 25,000 people in the United Kingdom die from preventable hospital-acquired venous thromboembolism every year. The incidence of DVT in elective foot and ankle surgery has been demonstrated to range from 0.22 percent to 3.5 percent. Chemical thromboprophylaxis has known complications, including increased bleeding, wound problems, and heparin-induced thrombocytopenia.

“Thromboembolic disease is associated with a high degree of morbidity and mortality,” Dr. Griffiths said. “The pressure to prescribe chemical thromboprophylaxis postoperatively for all orthopaedic patients undergoing elective procedures, including foot and ankle surgery, is increasing. The risk of clinically significant thromboembolic disease is so low in elective foot and ankle surgery, however, that chemical thromboprophylaxis is not indicated, regardless of patient risk factors.”

DVT and PE in Achilles injuries
In another presentation, Arush Patel, MD, reported results of a study evaluating the risk of DVT and PE developing after Achilles tendon rupture. The study also indicates that the risk of DVT and PE in this setting is low and that routine use of anticoagulation measures may not be warranted.

The study, a retrospective analysis of a large U.S. healthcare management organization database, tracked 1,174 patients from January 2008 to March 2010 (27 months). Patients were stratified into the following groups:

• Surgical or nonsurgical treatment
• Age younger than 40 years or 40 years and older
• Patients with or without congestive heart failure
• Body mass index less than 30 or 30 or more

The nonsurgical group was treated with plantar-flexed immobilization. Symptomatic DVT or PE related to the Achilles tendon rupture was diagnosed within 3 months of the injury or surgery; all positive diagnoses had a chart review for confirmation. All patients with a DVT had positive duplex ultrasound, and PE diagnoses were confirmed with a computed tomography scan with intravenous contrast or ventilation perfusion lung scan. Polytrauma patients were excluded.

No patients at the center were routinely prescribed anticoagulation for Achilles rupture. The overall rate for DVT and PE in the entire group was 0.43 percent and 0.34 percent, respectively. “Surprisingly, every reported PE had no documented DVT,” Dr. Patel said, adding that physicians tend not to check for DVT once they detect a PE.

The rate for DVT in the surgical group, 0.42 percent, was not significantly different from that of the nonsurgical group (0.43 percent). Similarly, no significant difference was seen between the incidence of PE in the surgical group (0.21 percent) and the nonsurgical group (0.43 percent).

A significant difference (p = 0.031) was seen in the age stratified groups. Patients younger than 40 years had a zero incidence of DVT and PE, whereas those 40 years or older had an incidence of 0.69 percent and 0.55 percent, respectively. Neither body mass index nor congestive heart failure status were significant factors.

Dr. Patel noted that the incidence of DVT and PE after total knee and total hip arthroplasty has been extensively studied, in contrast to the association in Achilles injuries. “Although there is general consensus on the use of prophylactic antithrombotic therapy following hip and knee surgery, there is no agreement regarding prophylactic therapy following Achilles tendon ruptures,” he said.

Based on these findings, Dr. Patel and his colleagues recommend against routine administration of prophylactic anticoagulation. “The use of anticoagulation medications is not benign,” he said. “The Food and Drug Administration has stated that the common anticoagulant warfarin was among the top 10 drugs with serious side effects.” He did, however, recommend that patients 40 years and older should be closely monitored.

Although this was a large study with an all-inclusive patient population, it was a retrospective analysis. Dr. Patel also noted the possibility of coding errors and insufficient power.

“A follow-up large prospective randomized clinical study to establish the incidence of DVT and PE following Achilles tendon rupture would be ideal,” Dr. Patel said.

The coauthors of Dr. Griffiths’ study are Christopher J. Pearce, MBCHB, FRCS; and James Calder, MD. Dr. Patel’s coauthors are Timothy Charlton, MD; David Thordarson, MD; and Brent Ogawa, MD.

Disclosure information: Dr. Calder—Smith & Nephew; DePuy; DJ Orthopaedics, JBJS–British; Knee Surgery; Sports Traumatology; Arthroscopy. Dr. Charlton—Biomet; Foot and Ankle International. Dr. Thordarson—DePuy; Orthohelix; Foot and Ankle International; Wolters Kluwer Health; Lippincott Williams & Wilkins; AOFAS. The remaining authors reported no conflicts.

Bottom Line

• Literature on DVT and PE and the risks and benefits of thromboprophylaxis in foot and ankle ankle surgery is relatively limited, with little evidence-based guidance.
• A British study comparing 3 years of patient data with chemoprophylaxis and 4 years of patient data with no prophylaxis for patients undergoing elective foot and ankle surgery found no benefit to chemoprophylaxis.
• Similarly, a retrospective American study found no need for thromboembolism prophylaxis in patients with ruptured Achilles tendons; patients older than age 40, however, should be closely monitored.
• Use of chemoprophylaxis for DVT and PE carries risks, including increased bleeding and heparin-induced thrombocytopenia.

Recommendations on DVT prophylaxis
Following the presentations by Drs. Griffiths and Patel, David R. Richardson, MD, reviewed the current literature and consensus regarding DVT and PE prophylaxis and provided some recommendations.

The Agency for Healthcare Research and Quality has called DVT and PE the most common preventable cause of hospital death in the United States, stating that the provision of appropriate prophylaxis is the paramount effective strategy to improve patient safety.

The literature strongly supports thromboprophylaxis for hip and knee surgical procedures, but is inconclusive regarding foot and ankle surgery; routine use is not recommended, Dr. Richardson said.

A survey of AOFAS and British Orthopaedic Foot Surgery Society members found that 19 percent of them routinely use thromboprophylaxis in either elective or trauma foot and ankle surgery. Reasons given for not using it include lack of published data and the belief that the rates of DVT and PE are low.

The AAOS has no specific recommendations for DVT prophylaxis after foot and ankle surgery; the American College of Chest Physicians does not recommend routine use of thromboprophylaxis for patients with isolated lower extremity injuries distal to the knee, nor does it recommend screening in asymptomatic patients.

Dr. Richardson conducts a thorough history and physical, evaluating for risk of thromboembolism and/or bleeding. Some of the factors he considers are obesity (BMI >35), smoking, previous DVT, and current contraceptive use. If the patient is on long-term anticoagulation treatment, the primary care physician should be consulted.

Dr. Richardson uses regional anesthesia when possible. He recommends use of a contralateral foot pump and/or compressive stockings for surgical cases expected to last more than 1 to 1.5 hours, and he advises using an ankle tourniquet when possible.

No prophylaxis is needed for patients who have zero or one risk factor for DVT or PE, and major bleeding; they are not immobilized and are full weight bearing. For patients immobilized with or without full weight bearing, he prescribes an enteric-coated acetylsalicylic acid (ECASA) regimen for 10 days. If such a patient insists on traveling within 10 days of surgery, he prescribes fondaparinux for 10 days.

For patients with two or more risk factors, he prescribes ECASA or fondaparinux for 10 days. Patients on long-term anticoagulation should resume the preoperative regimen on day one postoperatively, and bridging therapy should be provided as needed.

Dr. Richardson does not routinely screen for DVT and PE and uses venous duplex ultrasound as needed.

AAOS Now
June 2011 Issue
http://www.aaos.org/news/aaosnow/jun11/clinical10.asp

Routine DVT, PE prophylaxis questionable in foot, ankle surgery.