Hi Maria,
Footdrop is a condition where your foot just hangs and you have no or limited ability to lift (dorsiflex) or move your foot outwards (avert). The cause is usually caused by damage to the peroneal nerve that runs down the outside of your knee and wraps around the head of the fibula. The damage can be caused by trauma (as in my case when I broke the fibula) or by scar tissue putting pressure on the nerve. Someone with footdrop generally wears a brace to hold their foot up otherwise they would forever be tripping up.
Hamish
