Don’t throw an antique frame away! Ask your picture framer if anything can be done to restore it. It may be the case that it is beyond repair, but there is no harm in asking.
In the past picture frames were put together by nail and glue and with the passing of time often the corners are left only hanging on by a nail or two and a whim and a prayer!
Your picture framer will take the frame apart, clean up the corners and if necessary take a slice of a damaged length and pin it back together.
If the corners are seriously damaged the framer may cut further into the moulding. Although you will end up with a smaller frame, you can always use it to frame another artwork. The moral of the story is, never throw antique frames away, they can always be brought back to life. Old mouldings are irreplaceable!