I was severely burned in an automobile accident (60%, 3rd degree) on June 6, 2006 -- and was completely unable to work for a couple years. It took a little over 4 years total from the date of the accident till I got another job.
Every job since then has been with a startup.
So at this point, while a 4-year gap will still be a downward multiplier to some, the effect will be relatively mild.
Better to focus on the the sheer inner strength it must take (which I, and almost all these people summarily rejecting you, can only begin to imagine) to pull off a recovery like that, and how that makes a much more solid person overall -- and hence, a way better hire.