Combination strategy may best address DVT risk

A debate between two leading arthroplasty surgeons touched on several key issues relating to preventing deep vein thrombosis, including the paucity of scientific evidence supporting aspirin use, the efficacy of warfarin and other chemoprophylaxis measures for reducing pulmonary embolism, and how mechanical methods may complement each of these strategies.

Vincent D. Pellegrini Jr., MD, of the University of Maryland, who argued in favor of deep vein thrombosis (DVT) anticoagulation, faced off with Douglas E. Padgett, MD, of New York, who advocated for mechanical compression as a means to simultaneously reduce clots and mitigate bleeding complications.

Their debate at the Current Concepts in Joint Replacement 2010 Winter Meeting ultimately resulted in both physicians agreeing on the merits of using combined DVT prophylaxis methods while stratifying their use based on patient factors.

Vincent D. Pellegrini Jr.

Since preventing all venographically detected clots is unrealistic and could lead to bleeding problems, “This debate and discussion is really a matter of selecting the surrogate,” said Pellegrini, who reviewed the American College of Chest Physicians (ACCP) and American Academy of Orthopaedic Surgeon’s (AAOS) guidelines on DVT anticoagulation practices in patients undergoing total hip arthroplasty (THA).

“They have given a seal of approval to warfarin, fractionated heparin and fondaparinux,” with 35 days as the recommended duration of use and the ACCP came out against using aspirin in any setting, Pellegrini said, noting that due to concerns about bleeding risk in orthopedic patients the AAOS was displeased with those recommendations.

Therefore, when patients at increased risk of bleeding were considered, pharmaceuticals which elevated bleeding risk were eliminated as possible chemoprophylaxis measures by the AAOS guidelines and, “aspirin and warfarin are the only two drugs that survive,” Pellegrini explained.

Comparing clotting rates

Also, when there is an elevated risk of thrombosis and of bleeding, “… aspirin and warfarin still are the only ones, so bleeding risk trumps pulmonary embolism risk” in the AAOS guidelines Pellegrini said.

Venographic rates of residual clot formation of 10% to 20% with warfarin depend on general or regional anesthesia usage and clot rates for fractionated heparin are 10% or less, he said. “Our therapeutic compromise, if you will, is based on a balance and I accept less effective prevention of venographic disease to avoid bleeding complications, but still want highly effective prevention of clinical PE events.”

One version of the ACCP guidelines permitted mechanical prophylaxis in the immediate perioperative period as a management approach in cases with high bleeding risk. Once that risk resolves, Pellegrini argued chemoprophylaxis is indicated, as rates of proximal clots can be four times higher with pneumatic compression alone vs. chemoprophylaxis for THA.

Douglas E. Padgett

Padgett, who practices at the Hospital for Special Surgery, vehemently opposed DVT anticoagulation, saying, “I hope through logic and data to suggest that there are better and quite frankly safer alternatives to this, where current strategies to reduce VTE (venous thromboembolism) events are largely driven toward chemoprophylaxis.”

He noted, “The risk of thromboembolic problems is clearly well-documented. Therefore, to ignore or to avoid it, I think, is really not an option.”

Randomized study

A 411-patient multicenter randomized controlled study Padgett and colleagues conducted and published in the Journal of Bone and Joint Surgery in 2010 found no significant bleeding events and a 25% rate of minor bleeding events associated with using the device for THA. By comparison, controls treated with enoxaparin had a 6% rate of major and 31% rate of minor bleeds, he said. “However, we could not demonstrate a relationship between DVT and the use of the device. So where does that leave us?” he asked.

Pellegrini said that, while it demonstrated safety, the trial did not prove efficacy of the new device because of the small number of patients in the study.

One concept Padgett broached was revisiting the basic assumption that if limb torsion is associated with restriction of blood flow, which leads to stasis, and stasis leads to thrombosis, then mechanical DVT prevention modalities can theoretically result in nearly complication-free VTE prophylaxis.

Pellegrini said the greater proximal clot rates seen after use of mechanical devices alone were likely due to intimal injury in the femoral vein that occurred when positioning the leg to insert the femoral component; anticoagulants were likely needed to counteract this effect.

Padgett firmly rejected Pellegrini’s hypothesis that DVT anticoagulants are the standard of care.

“Anticoagulants are a potential major source of significant compromise after total joint replacement,” he said. – by Susan M. Rapp

References:

• Colwell CW, et al. J Bone Joint Surg Am. 2010 Mar;92(3):527-535.
• Padgett DE. DVT anticoagulants: Contemporary standard of care — opposes. Paper #24.
• Pellegrini VD. DVT anticoagulants: Contemporary standard of care — affirms. Paper #23. Both presented at the Current Concepts in Joint Replacement 2010 Winter Meeting. December 8-11, 2010. Orlando, Fla.

• Douglas E. Padgett, MD, HSS chief of adult reconstruction and joint replacement, can be reached at 535 East 70th St., New York, NY 10021; 212-606-1642; e-mail: padgettd@hss.edu.
• Vincent D. Pellegrini Jr., MD, the James L. Kernan Professor and Chair at University of Maryland School of Medicine, can be reached at the Department of Orthopaedics, 22 South Greene St., Suite S11B, Baltimore, MD 21201; 410-328-6040; email: vpellegrini@umoa.umm.edu.
• Disclosures: Padgett is a consultant to Stryker. Pellegrini is a consultant to Covidien’s medical advisory board for pneumatic compression education.

The optimal mode of thromboembolic prophylaxis for patients undergoing THA remains unknown. Dr. Pellegrini and Dr. Padgett have highlighted in their debate the issues of balancing efficacy against the risks of bleeding that can be associated with the use of pharmacological agents. Among the many issues that cloud this controversy are incomplete agreement on appropriate endpoints for measuring outcomes (DVT identified on imaging studies as opposed to symptomatic thromboembolic events), differing recommendations from the AAOS and ACCP, and a lack of adequately powered studies.

In the end, both speakers agreed on the wisdom of a multimodal approach combined with a “patient specific” strategy that tailors thromboembolic prophylaxis based on the risks (or perceived risks, as we presently have no clear methodology for determining risks objectively) of both thromboembolic events and bleeding. In the future, additional work into defining individual patient risks that correlate with patient centric outcomes (overall risk of mortality, readmission and other complications) will hopefully improve our ability to minimize complications following THA.

— Craig J. Della Valle, MD
Department of Orthopaedic Surgery, Rush University Medical Center, Chicago
Orthopedics Today Editorial Board member
Disclosure: He has no relevant financial disclosure.