The announcement Tuesday was made at the Reagan Presidential Library in Simi Valley, where she was expected to attend a speech by House Budget Committee Chairman Paul Ryan of Wisconsin.
Library executive director John Heubusch said from the stage that the former first lady was unable to attend because of her injury and was watching the event on TV at home.
Her spokeswoman Joanne Drake says Reagan has been adding a few appointments to her schedule but was advised by her doctor not to attend large events.
Heubusch says the fall at her Los Angeles home happened about six weeks ago.
The former first lady is 90 years old.
