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Preventing Pelvic Clots after Total Hip Replacement

Doctors agree that patients having a total hip replacement (THR) are at risk for blood clots. But what's the best way to prevent blood clots from forming? Should a blood thinner be given before the operation? During or after the operation?

In this study two groups of total hip patients were compared. All patients were at high risk for blood clots. Risk factors included age (over 65 years), obesity, heart disease, and previous history of a blood clot. Another word for 'clot' is thrombus (one blood clot) or thrombi (more than one clot).

One group got a single dose of heparin, a blood thinner used to prevent blood clots. The drug was given by IV about halfway through the operation but before the hip was replaced. A second group of total hip patients received a single dose of saline (salt) solution in the same way at the same time.

After the operation patients in both groups took aspirin (325 mg) twice a day for one month. Everyone was up and walking the day after the surgery. A special imaging test called magnetic resonance venography (MRV) was used to look for signs of blood clots.

They did not find any clots in the lower part of the leg that was operated on in the heparin group. They did find clots higher up in the pelvic area. This suggests pelvic clots may form at a different time during the surgery. Overall the heparin group didn't have fewer blood clots. In fact there were slightly more blood clots in this group compared to the control (saline) group.

The authors report this study was actually stopped early. Another study showed the use of pneumatic compression was better than intraoperative heparin in reducing blood clots. Foot and ankle motion are also used along with early walking. Heparin can still be used to prevent thrombi in the lower leg.

References: Geoffrey H. Westrich, MD, et al. The Effect of Intraoperative Heparin Administered During Total Hip Arthroplasty on the Incidence of Proximal Deep Vein Thrombosis Assessed by Magnetic Resonance Venography. In The Journal of Arthroplasty. January 2005. Vol. 20. No. 1. Pp. 42-50.

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