AAOS Exclusive: Mobile Compression Device Better Than Blood Thinners in Preventing Blood Clots

Venous thromboembolic events are a common complication following total hip arthroplasty (THA). These events can take the form of either deep vein thrombosis (DVT) or pulmonary emboli (PE). Clifford W. Colwell Jr, M.D., a Scripps Health orthopedic surgeon based in La Jolla, Calif., conducted a study that sought to determine whether using a mobile compression device without aspirin was as good at preventing VTEs as using one without aspirin.

Aspirin, of course, thins blood, which helps avoid clotting. However, this can pose the added complication of an increase in wound healing time due to excess bleeding. Colwell has also studied the effects of the drugs enoxaparin and warfarin, both blood thinners, in preventing clotting (1999). While Enoxaparin emerged as more effective in preventing VTEs during hospitalization, according to the study, this benefit was lost after the medication was discontinued, with no difference in the prevalence of venous thromboembolic disease between the two groups at three months after discharge from the hospital.

Colwell and his Scripps colleagues now officially recommend the use of a compression device over blood thinners post-THA.

“Blood thinners have long been considered the standard of care to prevent blood clots after orthopedic surgery, but they can have side effects that are concerning for many patients,” said Colwell on the Scripps website. “Through this research, we have found and established an equally effective means of accomplishing the same goal with an added layer of safety for patients.”

The recommendation is not uncontroversial. After Colwell’s presentation of the study at 2014 Annual Meeting of the American Academy or Orthopaedic Surgeons in New Orleans, La., his colleagues in the audience engaged in some good-natured debate about which methods are better. Some were adamant that blood thinners were the better option, and they have indeed been the gold standard for years.

“When we first looked into enoxaparin, the timing was different,” Colwell said during his presentation. “They used a pre-operative dose of 40 ml, then 40 ml once a day post-operatively. No one was willing to use pre-operative dosage [in the compression device/aspirin study]. We changed that dose to 30 ml twice daily no sooner than 12 hours post-op, but the average was 18 hours after. The bleeding rates were significant. There were major bleeds in the 4 to 5 percent range.”

Out of the 1,509 patients studied, eight (0.53 percent) had VTE (four distal DVT, one proximal DVT and three PEs). No deaths occurred. The study concluded that when compared to current pharmacologic protocols, the use of a portable compression device with or without aspirin for patients undergoing primary THA provides a non-inferior risk for developing VTE without the risk of bleeding—in other words, using aspirin does not make a meaningful difference in outcome.

“We know [using a compression device] increases blood flow, but does increased flow really do anything to DVT rate?” commented Colwell. “We don’t know. No one has been able to say is flow is better than thinning or vice versa, clinically.

“With the American College of Clinical Pharmacy stating that risk-benefits must be considered for prophylaxis with regards to bleeding versus efficacy—now that we have evidence that compression is equivalent and safer, shouldn’t that be discussed with the patient?” Colwell continued. “That’s why we did this study. All of us surgeons are concerned with bleeding rate. To me personally, I’m going to use a device over a blood thinner. Why take a risk? I think there’s going to be a paradigm shift.”

The device used in the study was the ActiveCare+S.F.T. made by Medical Compression Systems Inc., a company based Israel that focuses on treatment for VTE. The device is for both hospital and home use.