There are set of nerves which comes from spinal cord
and sends the information to the brain. (nerves are like electric wires which conducts electricity form main switch to appliance in the same fashion the nerves collects information from surrounding and sends the information to brain to analysis, for example if you put your leg in fire, the nerve will say its hot, the information passes to brain and brain will reply to remove the leg from the fire its very fast process, as it happens in fraction of second)
Now the nerve passes near the hip and joints back to spinal cord on the back of the hip bone
, so every nerves in the leg region have to traverse the hip area to enter the spinal cord, now the there are to many chances to impinge the nerve at any area, as they are long route was well as multiple in number, so the nerve which is crushed/ got impinge in any fracture
crack will result in numbness
of the area which it supplies, hence you are not feeling any thing in feet raise a strong suspicion of nerve being severed at any location about the loss of feeling as all nerves travel in up direction from leg to meet spinal cord.
Now their are chance of permanent changes if nerve is damage / may be a temporary change if nerve are intact but the prolonged pressure from cast may give rise to such problems can only be determined by further investigation.
Hope it helps.