Later Tuesday, the Flyers announced the signing of defenseman Michael Del Zotto to a one-year contract. Del Zotto finished last season with Nashville after being traded from the New York Rangers.
Timonen considered retiring after last season but in June signed a one-year contract extension that could be worth up to $3.5 million. He played 77 games last season, collecting six goals and 29 assists, and was named the team's best defender for the third straight year.
A blood clot in Timonen's left ankle sidelined him for the first four games of the 2008 Eastern Conference finals against Pittsburgh. That clot developed after he was struck by a puck during the previous playoff series against Montreal. Hextall said he did not know if Timonen's medical history caused him to be predisposed to blood clots.
"But I guess it's easy to speculate since it's happened again," the general manager said.
Hextall said he learned of Timonen's condition Monday morning. The defenseman felt pain in his calf and thought he had pulled a muscle. Timonen's friend, who Hextall said was a doctor, told him he should go to the hospital. Hextall said he had not talked to Timonen, but he said the defenseman sent him a text message.
"He seemed very frustrated," Hextall said. "But I think we're all happy for Kimmo and his three children that he's doing fine."
The Flyers have zeroed in on defense in the last three drafts, selecting five blue-liners in the first three rounds.
Shayne Gostisbehere (third round, 2012) signed with the team in April after leading Union College to the NCAA title. Gostisbehere, 21, played two games last season with the Phantoms of the AHL.
If Gostisbehere does not make the Flyers, he will join Robert Hagg (second round, 2013) with the Phantoms. Samuel Morin (first round, 2013) is expected to spend his fourth straight season in the Quebec Major Junior Hockey League.
"I don't want to throw a kid into a situation that he's not ready for," Hextall said. "The way to protect yourself is to add a veteran if possible."