Steroids can cause tears/ruptures to muscles, tendons, ligaments more easily than if you're not using them. This is well known. Seems like Berto has been on PED's for quite some time.
I don´t know **** but why would athletes use them to heal injuries and better recovery if that´s true?
there are various PED. They are not all the same. HGH is used for example to accelerate healing. That is not what Berto tested positive for. PED that accelerate muscle development are the one know to cause specific muscle and ligament injuries because your body has not adjusted to it.