Minor Leg Injuries May Up Clot Risk

Even minor leg injuries, such as ankle sprains or pulled
muscles, increase the risk of potentially life-threatening blood clots, new
research suggests.

Having a recent minor leg injury, according to a study from the Netherlands'
Leiden University, was found to be associated with a threefold increase in the
risk of serious blood clots, such as deep vein leg clots and pulmonary embolism
(clots that travel to the lung).

Researchers concluded that as many as 8% of these serious blood clots may be
caused by minor leg injuries that are not serious enough to require a cast or
extended immobilization.

Having a recent minor leg injury was found to increase the risk 50-fold
among people with a genetic mutation linked to blood clots.

"These injuries should be taken more seriously than they are today,"
reseacher Frits R. Rosendaal, MD, PhD, tells WebMD. "Physicians need to be
aware that people who have minor leg injuries may be at increased
risk."

Leg Clots Can Be Deadly

Major leg injuries that require a cast, surgery, extended bed rest, or
immobilization are known risk factors for deep vein clots, known medically as
deep venous thrombosis or DVT.

These clots can turn deadly when they travel to the lungs.

It has not been clear whether common leg injuries that require little
treatment also impact risk. In a study designed to address the question,
Rosendaal and Leiden University colleagues recruited 2,471 patients with a
history of deep vein or lung blood clots.

These people completed questionnaires designed to determine if they had had
injuries, surgical procedures, plaster casts, or immobilizations because of
injury within one year of developing the clots.

Their answers were compared to those of 3,534 people who had no history of
deep vein thrombosis.

A total of 289 patients (11.7%) reported that they had experienced a minor
injury in the three months prior to a serious blood clot. By contrast, 154 of
the participants who had no history of clots (4.4%) reported experiencing a
minor injury within three months prior to completing the questionnaire.

Leg injuries, but not injuries to other parts of the body, were associated
with an increased risk for serious blood clots, and the association was
strongest in the months before the blood clots occurred.

Even minor leg injuries, such as sprains or muscle tears, often lead to
reduced mobility, and Rosendaal says this may explain the increase in risk.

Clot Risk Higher in Elderly, Obese

Pulmonologist Victor F. Tapson, MD, of Duke University Medical Center, has
studied deep vein blood clots for many years.

He says the new study should serve to raise awareness among doctors and
their patients.

"I don't think it would surprise most experts that minor leg injury
would be a risk factor for these clots, but it is not something that most
clinicians are aware of," he tells WebMD. "This is an important
paper."

The findings could be especially important for patients at high risk of
developing blood clots, such as those who are elderly, obese , or who have a family
history of blood clots.

"These people need to be aware that even minor injuries and a relatively
short duration of inactivity could lead to blood clotting," Richard C.
Becker, MD, director of the Duke Cardiovascular Thrombosis Center, tells
WebMD.

As many as three in 1,000 people develop deep vein clots each year. Although
most people who experience minor leg injuries have little to worry about,
Rosendaal says everyone should be aware that such injuries can increase their
clot risk.

"If you sprain your ankle and your ankle hurts and is swollen, that is
to be expected," he says. "But if the calf or thigh begins to hurt or
swells too, that is not normal. And if you develop pulmonary symptoms like shortness of breath
or pain in the chest, don't ignore
them."

By Salynn Boyles
Reviewed by Louise Chang
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