The 28-year-old Ghana international ruptured his anterior cruciate ligament at the start of pre-season training, and is expected to be sidelined for most of the campaign.
Essien has not enjoyed the best of luck with injuries, but remains positive, and wrote on in his blog on the official Chelsea website: "The injury is well-documented so I will not dwell on it, however I can say I have had a good operation on my knee and I am definitely on the mend."
He added: "My days are filled with physio sessions from 10am to 5pm and it is a gradual process which I am confident will lead to the results I want.
"I have been here before and know the routine inside out now but it's still hard work as I hate to watch games on TV.
"I prefer to be with my team-mates in training and on the field of play, however I know I have to be patient so I can heal properly.
"I have been asked when I am coming back and at this point in time it's down to how the recovery goes and when I am given the all clear by the medical team.
"Sorry I can't be more precise, but its too early to give specific dates."
Source: PA
Source: PA