But Foxes physiotherapist Dave Rennie told BBC Radio Leicester that Tunchev has been making good progress.
"We are very hopeful that in the next three or four weeks he'll get back on the pitch and then it is a slow, steady process back to training," Rennie said.
Tunchev joined the Foxes in 2008 but has only started 20 league games and made a total of 29 appearances since then.
Rennie added: "He had the long-standing issue with his right knee where he had his cruciate problem - that's all sorted now and he's doing really well with that.
Aleksandar is just getting to the point where we can load him and this is the 'money-end' of the rehab process Leicester physio Dave Rennie "But unfortunately, in his final stages of his rehab from that, he hurt his other knee which required some further surgery.
"Aleksandar is just getting to the point where we can load him and this is the 'money-end' of the rehab process, so this is where we see how secure that knee will be for the rest of his career.
"He is very, very single-minded; he doesn't need too much cajoling. He is quite a tough nut and is desperate to get back out with the rest of the boys."