I think people missing something obvious IMO.
What is exactly wrong with Nigels back??
Does he need an operation which means he would be bed bound for 3/6 months?
As an employer, you should take in to consideration all factors, if you think he is going to be out for a prolonged period, why would you, potentialy, throw money down the drain, so to speak. Nige has had health issues previously.
Now, im not saying I agree with this at all, just playing devils advocate.