Beating blood clots: Reducing your risk before hip replacement surgery

Risk factors for venous thromboembolism after total hip replacement (THR) surgery were identified in a new study published in the September 2010 issue of The Journal of Bone and Joint Surgery (JBJS). While the rate of thromboembolism has been significantly reduced through medication, understanding the risk factors could further reduce the likelihood of patients developing this potentially fatal complication.

Two of the most common manifestations of a thromboembolism include:

• Deep vein thrombosis (DVT), in which the blood clot forms in a deep vein, commonly in the thigh or calf; and
  
• Pulmonary embolism (PE), in which the blood clot breaks free and travels through the veins.

"Risk of 1 percent may seem low, but it is clinically relevant," said Alma P. Pedersen, M.D., Ph.D., one of the co-authors of the study, and a staff specialist in the department of clinical epidemiology at Aarhus University Hospital in Aarhus, Denmark.

In this study, researchers reviewed the cases of more than 67,000 Danish patients who received total hip replacements over a 10-year span. They found that the overall incidence of venous thromboembolism did not change during that decade. In addition, the researchers identified a number of co-morbidity factors that increased a patient's likelihood of a DVT or PE, including:

• previous hospitalization for a DVT or PE;
  
• previous hospitalization for cardiovascular or cerebrovascular diseases; and
  
• presence of other diseases or disorders before THR surgery, including dementia, chronic pulmonary disease, connective tissue disease and ulcer disease.

In addition, patients with rheumatoid arthritis had reduced risk of a DVT or PE compared with those with osteoarthritis. "According to previous literature, we expected the opposite results," says Dr. Pedersen.

To prevent venous thromboembolism, patients who undergo a total hip replacement need to know about the symptoms of a blood clot, so that - if suspected - treatment is not delayed. If any symptoms of a blood clot arise, you should seek medical attention immediately.

These symptoms include:

• For DVT—leg pain, swelling, redness, and/or warmth in the limb or calf; and
  
• For PE — anxiety, shortness of breath, chest pain, coughing, coughing up blood, leg pain and swelling, or palpitations.

The rate of total hip replacements continues to grow:

• In 2008, more than 277,000 total hip replacements were performed in the U.S.; this number represents an increase of nearly 50 percent in the last decade. While THR is considered a safe procedure, conducting ongoing and additional research in thromboembolism risk factors clearly has the potential to save many lives.
  
• As travel can create greater risk for a blood clot post surgery, there are things like leg exercises and ankle pumps that you can do to lessen your risk. View the complete traveler's checklist, also available at www.aaos.org/dvt .

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