All injuries can heal but usually never to the status where they would be if the injury didn't occur in the first place. That's not to say that it can't be faster, stronger, and more powerful. It just means that it will probably be less so than if it were never injured in the first place. Also, previous injuries to the musculotendonous unit are more likely to be reinjured.
As indicated above post-injury rehab is very important to ensure that the injury not only heals but heals in the correct way with minimal residual side effects.