Flyers defenseman Kimmo Timonen, who has missed the entire season because of blood clots, is going to attempt to make a comeback.

Timonen, 39, will skate at practice Friday, the Flyers announced.

GM Ron Hextall announced recently that Timonen's clots had cleared from his lungs, but not his right calf.

Last week, Hextall called the situation the "most complex medical thing I've ever been through."

Timonen is a four-time all-star whom winger Jake Voracek said is "the piece we've been missing."

Some doctors believe it is risky for him to return.

Timonen said that he, his mother and two brothers have a protein C deficiency, which causes a greater disposition to blood clots. According to the National Institutes of Health, a mild case of protein C deficiency affects 1 in 500 people.

(More coming after a news conference after Thursday's first period.)