Very much dependends on the situation. How bad was your knee, and how well will the op go.
Some people bounch back very well and may be able to continue work, others not so lucky. I think you'll have to wait for your results. I'd be positive though, we don't know the details of your duty, your work ethic, your attitude to IHR, could you drop down to a shorter contract, transfer to a Mail Centre?
IHR is a long way down the road, I don't think you need the added strees of worrying about that just now. Good luck with the op.
