HST, he elbow problem Bryan referred to was a temporary inflammation condition. IK's condition is permanent physical deformity (disc thinning) and his disc will deteriorate further in the future. The temporary side effect of inflammation will heal with time and, perhaps, anti inflammatory drugs. When that temporary condition has healed sufficiently he can then continue on light deads. That is very similar advice as to what Bryan gave for the temporary elbow situation.
The lower back muscles are susceptible to injury during normal activities and weight training because as the body ages, the back loses flexibility and muscle elasticity. In the case of IK, he has a compressed disc at S1-L5. Hyperextensions are the worst thing he could due in the gym to aggravate the condition. Even not going beyond parallel and effectively eliminating the "hyper" portion of the exercise, may cause irreparable harm because he will be compressing that disc further.
However, HST, knowing from the past about how your mind can never be changed and the fact that I do not want to get into a wasted rounds of postings with you as many have been sucked in to in the past, this is my last post on this topic. This is my opinion based on my experience and consultations with many back surgeons, neurologists, physical therapists, etc. A simple search of the web will also confirm it although I dare say that you can probably find a site or two, probably a bro-bodybuilding site, that will say the opposite. If you want to do hyperextensions yourself when you have a permanent back problem, you have my blessing.
IK, make sure you incorporate appropriate stretching of the back and hams on a regular basis as that will relieve some of the pressure. BTW, I have gone from 5'10" at age 17 to a current 5'7-1/2" after my last surgery. The good news is I save a bit on groceries.