Below is copied off of other forums that fit your your situation:
Wing bones are pneumatic. They have air in them as that's the design of birds. If the bird's wing is amputated, an avian vet will amputate in the middle of the bone, not usually between joints. The reasoning is that the joint will continue to product joint fluid for its life, filly the recess with fluid that must be drained. A cleanly cut bone will leak air into the recess for approximately a week until it seals and then the air disappears and it no longer leaks. This sort of thing is obviously best done by a vet. *by threehorses*
Another person commented that their Vet was going to charge $300 for removal of wing. Now that is too much in my book.
Now this is crazy, I've never done this but if it comes to saving a life, and I have no options I go to old school methods. I'd buy a whole unfrozen chicken at the store, use this chicken as a learning about bone deal. Cut meat off and examine bone so you know where you need to cut your chickens bone. Make a clean cut somewhere along the bone but a good place that will allow the bone to lay flat and not stick up. Have sharp sterilized sheers, cut the store bought chicken's bone where you want your chicken's bone cut, maybe just above the joint but not the joint. See above threehorses comment why not the joint. Do it quick and fast, practice again on the other side, then do your live chicken. You will need help and this will be very gut wrenching, but if it means saving her life, do it. If you can not, then ask a guy or neighbor or anyone who butchers chickens or has the guts and confidence to do it. My stomach hurts just thinking about this process, but I think it needs done to save her life.
Before I'd attempt such a thing as above, I'd beg and plea with my regular country Vet(not a city pet only vet), offer a set amount of what it is worth to you, tell him you will not hold him accountable for anything that goes wrong, that you will help, but chicken will have to do this with out anesthesia(this is the bulk of the expense). Perhaps he will have other ways of knowing how to numb the pain or at least make the chicken woozy so less pain. If it is juts cutting the protruding bone shorter, which sounds like your case, it should be fairly easy. I can guarantee your chicken is in pain right now so don't think your doing it any disservice with this short term pain, if there is any.
She will need to be on a heavy does of antibiotics. I recommend penicillin or baytril. Another reason to go to your Vet, to get antibiotic, if you don't already have some. Do injectables(oral not as effective) and ask your Vet how to administer. Insist on giving the shot yourself with his assistance. This will be a very valuable thing to know, and boost your confidence in future shots and will come in handy for years to come with chicken care. It is not that hard, it is just getting the guts and confidence to do it. I had to go on U-tube and find how to do it. When it comes to life or death, you will be amazed at what you are able to do. I never thought in a million years I could dig out a stinking rotten hole in my chicken oozing with 100's of maggots from fly-strike. I saved her, and have learned so much from the experience.
On the not eating, use drops of water in mouth, plenty of it, Gatorade to keep electrolytes up, that is if you do not have chicken electrolytes products, which would be better. If no Gatorade, then sugar water and just a tiny pinch of salt. Dehydration is the most common death of all illnesses. Try scrambling some eggs for her to eat, or soft bread crumbs. But for sure the electrolytes and water if not eating.
Electrolytes are primarily composed of the minerals sodium, potassium, magnesium, calcium, plus chloride, phosphates and sulfates. They are essential for the functioning of your cells and organs! You can survive a long time without eating solid foods but need these in the fluids.
