As you say being an in patient at a hospital a kilt wouldn't be very practical for wearing 24 hours a day. Getting in and out of bed would be a factor and hospitals are always very hot so shorts sounds like a good option. While wearing a kilt to go visiting at hospitals, I've often encountered kilted men sitting in wheelchairs in the grounds, sometimes being pushed by an able bodied relative or nurse, so it seems that at least in Scotland here, it is relatively common for patients to take a kilt along with them to hospital for wearing for a few hours during the day to get out of the ward. A kilt would be easier for a patient to strap on rather than trying to pull on a pair of long trousers.