Top knee specialist Dr Richard Steadman told the Manchester
United ace he will only learn if surgery has worked when he returns
to action.
England midfielder Hargreaves has targeted a first-team return
in December after more than a year out of the side.
Only then will he discover whether his knee complaint has fully
cleared up.
He flew to Germany in July for a second opinion from specialist
Hans Muller-Wolfahrt, who was his physio at Bayern Munich.
Hargreaves, 28, has been back at United for just over a
week.
He has yet to start running again but he has been stepping up
his gym work at the Carrington training ground.
Hargreaves is on a special 45-minute workout regime to regain
the strength in his leg muscles and his general conditioning.
That is expected to be enhanced this week with some light
running, but there is no pressure on him to return.
A United source said: "With this type of injury, it either heals
or it doesn't. It's been great to have Owen back and he's really
positive, but even he doesn't know the answers.
"Dr Steadman said he will only find out if the surgical
procedures have been a success when he starts playing.
"Everyone is hoping for the best because he's such a great
player."