England all-rounder Andrew Flintoff has sustained a minor deep vein thrombosis in his right calf after undergoing knee surgery, the England and Wales Cricket Board said on Sunday.
"Andrew Flintoff recently suffered a common complication of surgery, a minor deep vein thrombosis in his right calf," a statement said.
"This will require a simple course of treatment and will not complicate his recovery from surgery."
Flintoff, 31, underwent surgery on his right knee the day after England regained the Ashes at the Oval last month.
He announced his retirement from test cricket before the Lord's test after the latest in a series of career-threatening injuries and will now concentrate on the one-day game.