Helen I broke my ankle a couple of years ago. After it was pinned it was in pot as you describe and I had to be none weight bearing. I also had to keep my leg elevated as much as possible to reduce swelling. I was able to do some limited work from home taking very frequent breaks from the PC so I could elevate my leg. Only once the pot came off did I return to work on reduced hours and I still had to follow a programme of physio therapy exercises in the office. So I think its a little more complicated than saying "as many hours as they can handle" I would get the person to discuss this with their surgeon and get a little more advice about what they need to do during the none weight bearing period as its unlikely they will be able to sit down at a desk, while traveling etc without harming their recovery. Also would their be any problems during an emergency evacuation of the building. Hopping down stairs is not as easy as it may sound.

It all depends on your individual circumtances. We recently had a member of staff who ruptured his achilles tendon playing football. Several weeks in full leg plaster and several more in a half plaster. He was keen to return to work asap so we initially agreed a regime where he would do some work from home and some office based work. While at work he was located in a ground floor office adjacent to a fire exit, fire wardens were informed of his presence and we ensured that he did not have to walk long distances for anything. His hours were adjuted so that he could arrive and leave at off-peak periods. We we lucky in that we were able to do all of these things but it still took a lot of organisation.