Regarding the split cast point raised....i think it would be more appropriate for a medically qualified person to answer because I certainly am not, but i will offer my thoughts on the matter.....
I think it is advisable for the cast to be split if the pax is travelling with 48 hours or so of the accident, as swelling can be an issue after take off. Outside 48 hours, maybe swellin isn't such an issue, not no necessity to split the cast. I assume the issuing of a medical certificate would have taken into account the time apsect of things. It would be good for all to have to opinion of a qualified medical person on this subject.