Let's say around ~50 BC, I am with one of the (probably) hundreds of gentlemen who were wounded by the British chariots - In my case, my leg was injured in a way that it would never work again, and my friend merely develops a limp.
What happens to us?
I doubt they'd have what the gentlemen /r/Army or /r/Frenchforeignlegion might get, but was there any similar plan? (In the Legion, you get citizenship ((in the case you do not have it)) and a guaranteed job, and in the Army you get your medical treatments more-or-less paid for, and a check sent to you periodically depending on the percentage of your injuries).
Would someone with a severed arm be able to stay in a logistical manner?
I've written on this question in the past. There are also some links there to other threads with related info.
Of course, if anybody else has more to add, I for one would gladly read it.
I will stress that my answer tells you more about what would happen in 50 AD than in 50 BC, since the Roman army wasn't fully professional and institutionalised yet in the earlier period. Also we know a lot less about the older army.