1.
old wound; old scar
A physical wound or scar from the past that has healed but may still cause occasional pain or discomfort.
2.
past disgrace; old scandal; skeleton in the closet
A past mistake, scandal, or shameful event that one would rather keep hidden. Figurative usage.
Usage
In the literal sense, often used to describe scars or injuries that flare up in bad weather or at the change of seasons. In the figurative sense, refers to past mistakes or scandals, especially ones that can be used against someone. The expression 古傷をえぐる means "to reopen old wounds" or "to bring up painful past events."