But the England international said: "I wouldn't say I am pain free and I don't know if I can play through it.
"I am still in the process of getting injections to try to manage the pain."
Hargreaves will feature in another reserve team fixture on Thursday as he nears a first-team return but he concedes that there is a chance he will never be fully clear of the problem.
And renowned Colorado-based surgeon Dr Richard Steadman told the midfielder his knees were in a worse state than he had ever come across in 35 years of practicing.
Hopefully I will be fit this season, and going forward I will be able to play another six, seven or eight years Owen Hargreaves "My training has improved over the last weeks and that is a very positive sign for me. I believe that it will continue to improve and progress," Hargreaves said.
"It's about training, getting these injections and trying to go forward."
The problematic injury first surfaced during his last season at Bayern Munich before Hargreaves managed to feature in 25 games during his debut Old Trafford campaign in 2007/08.
"My first season at United I had the pain and was able to play through it but basically I shouldn't have been playing," he added.
"In the end, the pain was just too high and I had to have surgery.
"I wouldn't wish it on anyone. There were massive operations, very severe, and a lot of the treatments since have been slightly experimental. You have to try what works."
Can Hargreaves force his way back into the United team? "It's difficult to describe the pain. It's just pain," Hargreaves continued.
"At least the surgery did it's job because before the operation my tendons obviously weren't in the greatest condition.
"I would like to progress from this point even more. Hopefully I will be fit this season, and going forward I will be able to play another six, seven or eight years.
"Football is a physical game and injuries are part of it. But I could never imagine having one that has impacted on me so much.
"I thought - everyone thought - I would be fit for the start of the season. It didn't materialise.
"It has been a pretty humbling experience and I am sure many people doubted me, but anybody who knows me, knows that what I set my mind to, I get."