Will a cortisone injection work?

I had an ankle arthroscopy operation in April this year for an ankle injury which occured when I fell over in April 2009.  I have received 9 x physio sessions but there is no improvement.  I am still using a walking stick and unable to do normal activities.  My consultant referred me for an ultra sound as he feels I may have a nueroma.  The pain is indentical to that prior to the operation so I feel I have taken a step backwards.  The radiographer however, referred my case back to consultant advising that an MRI scan would give a better prognosis.  I have been given an urgent appointment to see my consultant and understand that I will be given a cortisone injection instead - will this guarantee a full recovery?  I am at the point of being re-deployed and any assistance would be greatly appreciated. Thanks