Between 9.30am and 11am on Tuesday 23 June 2015, the 46-year-old got off at Shudehill bus station to get a tram to Salford, where he works.
As he was waiting, he was knocked to the floor and had his bag stolen.
He is now in a critical condition in hospital.
Police do not yet know whether the robbery caused these serious injuries or whether they are as a result of a pre-existing medical condition.
Detective Constable Sarah Wright said: “We have not been able to speak to him yet and we are keen to hear from anyone who may have witnessed what happened to come forward.
“It would have been busy at that time and we believe someone may have seen the robbery.
“If you did, and you can also provide a description of the offender, please call us as soon as possible.”
Anyone with information should phone police on 0161 856 3522 or the independent charity Crimestoppers, anonymously on 0800 555 111.
