Pennington underwent surgery at Lenox Hill Hospital and will be sidelined indefinitely. He was injured late in the first half of the game against the New York Giants when he landed awkwardly after being tackled from behind by linebacker Brandon Short.
"It's really unfortunate because we, as players, don't want to see anyone get hurt," said Giants defensive end Michael Strahan. "For him to get hurt in a preseason game is a shame."
Pennington will be out indefinitely.
Elsewhere, it was Washington 24, Baltimore 3; Buffalo 28, St. Louis 24; Tennessee 23, Cincinnati 15; Detroit 38, Cleveland 17; Carolina 20, Green Bay 7; Tampa Bay 10, Jacksonville 6; San Diego 19, Houston 17; San Francisco 27, New Orleans 12; and Seattle 42, Kansas City 31.