i can tell you that cortisone can weaken tendons and that some tendons, they say, really should never be injected.
the cortisone that i had injected into my wrists got rid of the scar tissue.....how could that happen if it weren't "sort of degrading" something......
i only get cortisone when a tendon has gotten to the point that a slight movement will break the scar tissue causing more inflammation and more scar tissue, and becomes a vicious cycle. once in my dq tendon, once in my ulnar wrist. i must have "weak" wrists to start with.
not as sure about how the cortisone to the SI works, but had that done once and it seemed to stabilize the joint, firmed up the ligaments in there. maybe by simply reducing the inflammation.
but, i've heard and read many times that cortisone can weaken tendons and that the achilles tendon shouldn't be injected. can't remember exactly why that tendon is more likely to rupture from cortisone, but i do remember reading that in several places.
sue