If I had/have a pre-existing injury will it be difficult to prove my workers’ compensation claim or get workers’ compensation benefits?

If you suffered an aggravation to a pre-existing condition, then the aggravation should be covered by the workers’ compensation insurance carrier. However, it mayl be more difficult to get workers compensation benefits as the workers’ compensation carrier will probably try to argue that the problems you are having are related to the pre-existing condition and not your new injury. That does not mean that it will be impossible to get the injuries covered, only that it will be more difficult.