how long is a workman's comp case open for?

[Shannon]

i have an employee who was injured this past winter.(lower lumbar back injury) he is now having more pain from this injury and the doctors are talking surgery. (DX with swelling between the vertebra, with potential of perminent nerve damage) how long is the case open for? he is trying to have this go back on the original claim to cover extensive medical bills. our person who handles the workman's comp says it's too late, the case is probably closed. he has already paid out of pocket for drs visit and scripts.This is in New York State