Factors that favor a herniated nucleus pulposus in the L spine

1. Preexisting disc degeneration with tears in the posterior annulus that allow a path for the flow of nuclear material

2. Sufficiently hydrated nucleus capable of exerting high intradiscal pressure

3. Inability of the posterior annulus to resist pressure from the migrating nucleus

4. Sustained or repetitive loading applied over a flexed and rotated spine

source: Donald A. Neumann, Kinesiology of The Musculoskeletal System, Foundations for Rehabilitation