I thinks its not normal at all beause you are having cold
sesnations and numbness
I think your leg splint
is too tight due to which blood supply restricts and causes numb foot.Recommendations:Try to do some anke pumps (moving your ankle towards your self and away from you in long sitting position),Elevate your foot to prevent swelling,Dont allow weight bearing on that foot,Cheak your medications for side effects, go for physiotherapy
hope this helps!!