ASHBURN, Va. (AP) _ Washington Redskins quarterback Brad Johnson is recovering from arthroscopic surgery on his left knee, performed after he experienced swelling following minicamp.

The operation, described by the Redskins as a precautionary procedure, was performed by Johnson's doctor in Minnesota on Tuesday.

Johnson felt the swelling at the end of the April 23-25 minicamp. The swelling subsided, but team physician Dr. Gordon Avery recommended surgery to alleviate the chance of a reoccurrence during the season.

In a statement released Wednesday, the Redskins said they expected Johnson to be ready for the start of training camp at the end of July.

Johnson was acquired in February from the Vikings in exchange for three draft picks.