Has a peripheral nerve problem from the injury been considered?

Foot drop doesn't only have to occur from central nervous system problems--a compressed nerve root in the lower spine, or an injury in one of the nerves lower down, from leg to foot, might also result in it. The nerve conduction study and EMG you have coming up might shed more light on that if done correctly and thoroughly.

You might want to peruse our peripheral neuropathy forum:

http://neurotalk.psychcentral.com/forum20.html

Also, this is a good article on nerve entrapment/compression sydromes of the lower extremities:

http://emedicine.medscape.com/article/1234809-overview