I can only speak from my experience. At 51 and making a serious effort at regaining my younger physique I decided to go the HGH route, and was fortunate enough to find a physician that supported my effort and prescribed Saizen HGH for me. I have ramped up from 1 iu daily to 3 iu, and I am now in my fourth month of useage.
Injury background is a severely crushed lower disc that happened 15 years ago, back pain has ranged from extreme to annoying ever since, with really no period of time where it wasn't present. In the last month the pain is non existent, other than occasional stiffness I would say that the injury seems to have vanished. Now, it is completely possible that my increased exercise regime has strengthened my core muscles which has relieved the pain, but I would have to add that I really have not been out of shape during the last 15 years. I would say the HGH at least passively helped the injury by allowing me to recover from work quicker and maintain a tighter rotation of exercise.
It has taken a solid 3+ months to see benefits from the HGH, and at 51 I am leaner and stronger than I have ever been and just starting to notice wrinkles are softening and skin is looking younger (giant benefit when you are over 50!). I think that HGH is a good idea for injury repair, but it would seem at lower, affordable doses, might take some time?