Obviously you have some nerve damage going on there. Did you have some nerve tests? Do you have the results from them?
What does the doctor say about the swelling? It's been a LONG time since the accident. It should NOT be swelling due to THAT. Not unless something is wrong.

I don't understand why it would still be swelling in just that ONE leg.

What does your doctor say about that?
Haven't you had any tingling or burning in that leg AT ALL? That would indicate that the nerves were trying to heal.
Talk to your doctor about it, and see what he says. God bless & please let us know. Maybe we can do some research for you. Take care. Hugs, Lee