Almost all individuals were born with “normal” discs. Degenerative changes occur with life experience and aging. Genetics does however play a significant role in the degenerative experience. Genetics cause the collagen fibers of the disc (in the annulus- see website) to have different tensile strengths in my opinion.
The more brittle the collagen, the greater propensity to tear. I have ten year olds in my practice with degenerative changes of the discs. I also have eighty year olds who have worked at hard labor with relatively normal discs.
You are talking about injury at work and causation. In many states, the workman’s compensation laws hold that an injury on the job or an aggravation of a preexisting condition caused by the occupation will be held to be compensable through workman’s compensation insurance.
Dr. Corenman