Hargreaves joined City on transfer deadline day after leaving Manchester United at the end of his contract in the summer.
Hargreaves struggled with injuries during his spell at United and made just four appearances in the last three seasons for the club.
Hargreaves scored in his debut for City earlier this week in the Carling Cup clash against Birmingham.
He said: “After my first season, I had a bit of a tendon problem but didn’t realise the magnitude of it. I played and it got a little bit worse.
“We treated it and it got significantly worse after that, through the injections I had. Basically, I was left to pick up the pieces, which was incredibly frustrating. That was surgery and that was 18 months gone.”
“You’d have to ask them [United] if my injuries were mishandled,” said Hargreaves. “There were a few crucial points at times. I played my whole first season. I received some injections and after that my tendon was never the same.
“After the injections, I tried to get back on my feet and they said my tendon was good, but it felt like I was made out of glass. That obviously had a huge impact.”
He added: “It’s difficult. All the people there are lovely. Everybody tries their best, but at times you come to a certain point where you need to make a decision.
“They said it would help and that I wouldn’t have any side effects from the injections. That obviously wasn’t the case and if I’d known I could have had a reaction like that, I wouldn’t have done it.
“It’s my career, I’m in it. I’m trying to get all this information. I’m hearing about tendons and before I didn’t know its real function. It was a s*** position to be in, to be honest.”
