This is a myth... HGH and other PEDs can do nothing for ligaments. This is their fatal flaw, which is why those that use PEDs end up having issues in their late career. Muscles grow,but ligaments stay the same leading to wear and tear a lot earlier.
Let me modify my statement, cause it may cause confusion. HGH has been shown to assist in fracture healing in studies, which is what Spencer has, but there are issues with it and all PEDs, ligaments being the primary issue. These imbalances lead to further issues down the road. Ligaments are not very flexible and when they do stretch, it's a bad sign, because they stabilize the joints. They don't regenerate in a manner muscles or bones to and if their is a rupture, they don't go back to their original state.
I personally don't see any issues with HGH for bone healing, because that is what medicine is suppose to do. But obviously, this has to be balanced with the PED issue. I'm not sure what the NFL stance is though in these scenarios...